diff --git a/osu.Game.Tests/Collections/IO/ImportCollectionsTest.cs b/osu.Game.Tests/Collections/IO/ImportCollectionsTest.cs
index 32503cdb12..604b87dc4c 100644
--- a/osu.Game.Tests/Collections/IO/ImportCollectionsTest.cs
+++ b/osu.Game.Tests/Collections/IO/ImportCollectionsTest.cs
@@ -12,7 +12,7 @@ using NUnit.Framework;
 using osu.Framework.Extensions;
 using osu.Framework.Platform;
 using osu.Framework.Testing;
-using osu.Game.Beatmaps;
+using osu.Game.Collections;
 using osu.Game.Database;
 using osu.Game.Tests.Resources;
 
@@ -34,7 +34,7 @@ namespace osu.Game.Tests.Collections.IO
 
                     osu.Realm.Run(realm =>
                     {
-                        var collections = realm.All<RealmBeatmapCollection>().ToList();
+                        var collections = realm.All<BeatmapCollection>().ToList();
                         Assert.That(collections.Count, Is.Zero);
                     });
                 }
@@ -58,7 +58,7 @@ namespace osu.Game.Tests.Collections.IO
 
                     osu.Realm.Run(realm =>
                     {
-                        var collections = realm.All<RealmBeatmapCollection>().ToList();
+                        var collections = realm.All<BeatmapCollection>().ToList();
                         Assert.That(collections.Count, Is.EqualTo(2));
 
                         // Even with no beatmaps imported, collections are tracking the hashes and will continue to.
@@ -93,7 +93,7 @@ namespace osu.Game.Tests.Collections.IO
 
                     osu.Realm.Run(realm =>
                     {
-                        var collections = realm.All<RealmBeatmapCollection>().ToList();
+                        var collections = realm.All<BeatmapCollection>().ToList();
 
                         Assert.That(collections.Count, Is.EqualTo(2));
 
@@ -141,7 +141,7 @@ namespace osu.Game.Tests.Collections.IO
                     Assert.That(exceptionThrown, Is.False);
                     osu.Realm.Run(realm =>
                     {
-                        var collections = realm.All<RealmBeatmapCollection>().ToList();
+                        var collections = realm.All<BeatmapCollection>().ToList();
                         Assert.That(collections.Count, Is.EqualTo(0));
                     });
                 }
@@ -171,7 +171,7 @@ namespace osu.Game.Tests.Collections.IO
                     // ReSharper disable once MethodHasAsyncOverload
                     osu.Realm.Write(realm =>
                     {
-                        var collections = realm.All<RealmBeatmapCollection>().ToList();
+                        var collections = realm.All<BeatmapCollection>().ToList();
 
                         // Move first beatmap from second collection into the first.
                         collections[0].BeatmapMD5Hashes.Add(collections[1].BeatmapMD5Hashes[0]);
@@ -196,7 +196,7 @@ namespace osu.Game.Tests.Collections.IO
 
                     osu.Realm.Run(realm =>
                     {
-                        var collections = realm.All<RealmBeatmapCollection>().ToList();
+                        var collections = realm.All<BeatmapCollection>().ToList();
                         Assert.That(collections.Count, Is.EqualTo(2));
 
                         Assert.That(collections[0].Name, Is.EqualTo("First"));
diff --git a/osu.Game.Tests/Visual/Collections/TestSceneManageCollectionsDialog.cs b/osu.Game.Tests/Visual/Collections/TestSceneManageCollectionsDialog.cs
index 21d2b0328b..8de38eb4e7 100644
--- a/osu.Game.Tests/Visual/Collections/TestSceneManageCollectionsDialog.cs
+++ b/osu.Game.Tests/Visual/Collections/TestSceneManageCollectionsDialog.cs
@@ -51,7 +51,7 @@ namespace osu.Game.Tests.Visual.Collections
         [SetUp]
         public void SetUp() => Schedule(() =>
         {
-            Realm.Write(r => r.RemoveAll<RealmBeatmapCollection>());
+            Realm.Write(r => r.RemoveAll<BeatmapCollection>());
             Child = dialog = new ManageCollectionsDialog();
         });
 
@@ -77,11 +77,11 @@ namespace osu.Game.Tests.Visual.Collections
         [Test]
         public void TestAddCollectionExternal()
         {
-            AddStep("add collection", () => Realm.Write(r => r.Add(new RealmBeatmapCollection(name: "First collection"))));
+            AddStep("add collection", () => Realm.Write(r => r.Add(new BeatmapCollection(name: "First collection"))));
             assertCollectionCount(1);
             assertCollectionName(0, "First collection");
 
-            AddStep("add another collection", () => Realm.Write(r => r.Add(new RealmBeatmapCollection(name: "Second collection"))));
+            AddStep("add another collection", () => Realm.Write(r => r.Add(new BeatmapCollection(name: "Second collection"))));
             assertCollectionCount(2);
             assertCollectionName(1, "Second collection");
         }
@@ -110,7 +110,7 @@ namespace osu.Game.Tests.Visual.Collections
             });
 
             // Done directly via the collection since InputManager methods cannot add text to textbox...
-            AddStep("change collection name", () => placeholderItem.Model.Name = "a");
+            AddStep("change collection name", () => placeholderItem.Model.PerformWrite(c => c.Name = "a"));
             assertCollectionCount(1);
             AddAssert("collection now exists", () => placeholderItem.Model.IsManaged);
 
@@ -120,7 +120,7 @@ namespace osu.Game.Tests.Visual.Collections
         [Test]
         public void TestRemoveCollectionExternal()
         {
-            RealmBeatmapCollection first = null!;
+            BeatmapCollection first = null!;
 
             AddStep("add two collections", () =>
             {
@@ -128,13 +128,13 @@ namespace osu.Game.Tests.Visual.Collections
                 {
                     r.Add(new[]
                     {
-                        first = new RealmBeatmapCollection(name: "1"),
-                        new RealmBeatmapCollection(name: "2"),
+                        first = new BeatmapCollection(name: "1"),
+                        new BeatmapCollection(name: "2"),
                     });
                 });
             });
 
-            AddStep("change first collection name", () => Realm.Write(r => r.Remove(first)));
+            AddStep("remove first collection", () => Realm.Write(r => r.Remove(first)));
             assertCollectionCount(1);
             assertCollectionName(0, "2");
         }
@@ -154,8 +154,8 @@ namespace osu.Game.Tests.Visual.Collections
             });
             AddStep("add two collections with same name", () => Realm.Write(r => r.Add(new[]
             {
-                new RealmBeatmapCollection(name: "1"),
-                new RealmBeatmapCollection(name: "1")
+                new BeatmapCollection(name: "1"),
+                new BeatmapCollection(name: "1")
                 {
                     BeatmapMD5Hashes = { beatmapManager.GetAllUsableBeatmapSets().First().Beatmaps[0].MD5Hash }
                 },
@@ -167,8 +167,8 @@ namespace osu.Game.Tests.Visual.Collections
         {
             AddStep("add two collections", () => Realm.Write(r => r.Add(new[]
             {
-                new RealmBeatmapCollection(name: "1"),
-                new RealmBeatmapCollection(name: "2")
+                new BeatmapCollection(name: "1"),
+                new BeatmapCollection(name: "2")
                 {
                     BeatmapMD5Hashes = { beatmapManager.GetAllUsableBeatmapSets().First().Beatmaps[0].MD5Hash }
                 },
@@ -207,7 +207,7 @@ namespace osu.Game.Tests.Visual.Collections
         {
             AddStep("add collection", () => Realm.Write(r => r.Add(new[]
             {
-                new RealmBeatmapCollection(name: "1")
+                new BeatmapCollection(name: "1")
                 {
                     BeatmapMD5Hashes = { beatmapManager.GetAllUsableBeatmapSets().First().Beatmaps[0].MD5Hash }
                 },
@@ -234,7 +234,7 @@ namespace osu.Game.Tests.Visual.Collections
         [Test]
         public void TestCollectionRenamedExternal()
         {
-            RealmBeatmapCollection first = null!;
+            BeatmapCollection first = null!;
 
             AddStep("add two collections", () =>
             {
@@ -242,8 +242,8 @@ namespace osu.Game.Tests.Visual.Collections
                 {
                     r.Add(new[]
                     {
-                        first = new RealmBeatmapCollection(name: "1"),
-                        new RealmBeatmapCollection(name: "2"),
+                        first = new BeatmapCollection(name: "1"),
+                        new BeatmapCollection(name: "2"),
                     });
                 });
             });
@@ -256,7 +256,7 @@ namespace osu.Game.Tests.Visual.Collections
         [Test]
         public void TestCollectionRenamedOnTextChange()
         {
-            RealmBeatmapCollection first = null!;
+            BeatmapCollection first = null!;
 
             AddStep("add two collections", () =>
             {
@@ -264,8 +264,8 @@ namespace osu.Game.Tests.Visual.Collections
                 {
                     r.Add(new[]
                     {
-                        first = new RealmBeatmapCollection(name: "1"),
-                        new RealmBeatmapCollection(name: "2"),
+                        first = new BeatmapCollection(name: "1"),
+                        new BeatmapCollection(name: "2"),
                     });
                 });
             });
diff --git a/osu.Game.Tests/Visual/SongSelect/TestSceneFilterControl.cs b/osu.Game.Tests/Visual/SongSelect/TestSceneFilterControl.cs
index e4d69334a3..2a4613c37b 100644
--- a/osu.Game.Tests/Visual/SongSelect/TestSceneFilterControl.cs
+++ b/osu.Game.Tests/Visual/SongSelect/TestSceneFilterControl.cs
@@ -48,7 +48,7 @@ namespace osu.Game.Tests.Visual.SongSelect
         [SetUp]
         public void SetUp() => Schedule(() =>
         {
-            Realm.Write(r => r.RemoveAll<RealmBeatmapCollection>());
+            Realm.Write(r => r.RemoveAll<BeatmapCollection>());
 
             Child = control = new FilterControl
             {
@@ -69,8 +69,8 @@ namespace osu.Game.Tests.Visual.SongSelect
         [Test]
         public void TestCollectionAddedToDropdown()
         {
-            AddStep("add collection", () => Realm.Write(r => r.Add(new RealmBeatmapCollection(name: "1"))));
-            AddStep("add collection", () => Realm.Write(r => r.Add(new RealmBeatmapCollection(name: "2"))));
+            AddStep("add collection", () => Realm.Write(r => r.Add(new BeatmapCollection(name: "1"))));
+            AddStep("add collection", () => Realm.Write(r => r.Add(new BeatmapCollection(name: "2"))));
             assertCollectionDropdownContains("1");
             assertCollectionDropdownContains("2");
         }
@@ -78,10 +78,10 @@ namespace osu.Game.Tests.Visual.SongSelect
         [Test]
         public void TestCollectionRemovedFromDropdown()
         {
-            var first = new RealmBeatmapCollection(name: "1");
+            var first = new BeatmapCollection(name: "1");
 
             AddStep("add collection", () => Realm.Write(r => r.Add(first)));
-            AddStep("add collection", () => Realm.Write(r => r.Add(new RealmBeatmapCollection(name: "2"))));
+            AddStep("add collection", () => Realm.Write(r => r.Add(new BeatmapCollection(name: "2"))));
             AddStep("remove collection", () => Realm.Write(r => r.Remove(first)));
 
             assertCollectionDropdownContains("1", false);
@@ -91,7 +91,7 @@ namespace osu.Game.Tests.Visual.SongSelect
         [Test]
         public void TestCollectionRenamed()
         {
-            AddStep("add collection", () => Realm.Write(r => r.Add(new RealmBeatmapCollection(name: "1"))));
+            AddStep("add collection", () => Realm.Write(r => r.Add(new BeatmapCollection(name: "1"))));
             AddStep("select collection", () =>
             {
                 var dropdown = control.ChildrenOfType<CollectionFilterDropdown>().Single();
@@ -118,7 +118,7 @@ namespace osu.Game.Tests.Visual.SongSelect
         public void TestCollectionFilterHasAddButton()
         {
             addExpandHeaderStep();
-            AddStep("add collection", () => Realm.Write(r => r.Add(new RealmBeatmapCollection(name: "1"))));
+            AddStep("add collection", () => Realm.Write(r => r.Add(new BeatmapCollection(name: "1"))));
             AddStep("hover collection", () => InputManager.MoveMouseTo(getAddOrRemoveButton(1)));
             AddAssert("collection has add button", () => getAddOrRemoveButton(1).IsPresent);
         }
@@ -128,7 +128,7 @@ namespace osu.Game.Tests.Visual.SongSelect
         {
             addExpandHeaderStep();
 
-            AddStep("add collection", () => Realm.Write(r => r.Add(new RealmBeatmapCollection(name: "1"))));
+            AddStep("add collection", () => Realm.Write(r => r.Add(new BeatmapCollection(name: "1"))));
 
             AddStep("select available beatmap", () => Beatmap.Value = beatmapManager.GetWorkingBeatmap(beatmapManager.GetAllUsableBeatmapSets().First().Beatmaps[0]));
             AddAssert("button enabled", () => getAddOrRemoveButton(1).Enabled.Value);
@@ -144,7 +144,7 @@ namespace osu.Game.Tests.Visual.SongSelect
 
             AddStep("select available beatmap", () => Beatmap.Value = beatmapManager.GetWorkingBeatmap(beatmapManager.GetAllUsableBeatmapSets().First().Beatmaps[0]));
 
-            AddStep("add collection", () => Realm.Write(r => r.Add(new RealmBeatmapCollection(name: "1"))));
+            AddStep("add collection", () => Realm.Write(r => r.Add(new BeatmapCollection(name: "1"))));
             AddAssert("button is plus", () => getAddOrRemoveButton(1).Icon.Equals(FontAwesome.Solid.PlusSquare));
 
             AddStep("add beatmap to collection", () => getFirstCollection().BeatmapMD5Hashes.Add(Beatmap.Value.BeatmapInfo.MD5Hash));
@@ -161,7 +161,7 @@ namespace osu.Game.Tests.Visual.SongSelect
 
             AddStep("select available beatmap", () => Beatmap.Value = beatmapManager.GetWorkingBeatmap(beatmapManager.GetAllUsableBeatmapSets().First().Beatmaps[0]));
 
-            AddStep("add collection", () => Realm.Write(r => r.Add(new RealmBeatmapCollection(name: "1"))));
+            AddStep("add collection", () => Realm.Write(r => r.Add(new BeatmapCollection(name: "1"))));
             AddAssert("button is plus", () => getAddOrRemoveButton(1).Icon.Equals(FontAwesome.Solid.PlusSquare));
 
             addClickAddOrRemoveButtonStep(1);
@@ -178,7 +178,7 @@ namespace osu.Game.Tests.Visual.SongSelect
         {
             addExpandHeaderStep();
 
-            AddStep("add collection", () => Realm.Write(r => r.Add(new RealmBeatmapCollection(name: "1"))));
+            AddStep("add collection", () => Realm.Write(r => r.Add(new BeatmapCollection(name: "1"))));
             AddStep("select collection", () =>
             {
                 InputManager.MoveMouseTo(getCollectionDropdownItems().ElementAt(1));
@@ -193,10 +193,10 @@ namespace osu.Game.Tests.Visual.SongSelect
                 InputManager.Click(MouseButton.Left);
             });
 
-            AddAssert("collection filter still selected", () => control.CreateCriteria().Collection?.Name.Value == "1");
+            AddAssert("collection filter still selected", () => control.CreateCriteria().Collection?.Name == "1");
         }
 
-        private RealmBeatmapCollection getFirstCollection() => Realm.Run(r => r.All<RealmBeatmapCollection>().First());
+        private BeatmapCollection getFirstCollection() => Realm.Run(r => r.All<BeatmapCollection>().First());
 
         private void assertCollectionHeaderDisplays(string collectionName, bool shouldDisplay = true)
             => AddAssert($"collection dropdown header displays '{collectionName}'",
diff --git a/osu.Game/Beatmaps/RealmBeatmapCollection.cs b/osu.Game/Beatmaps/RealmBeatmapCollection.cs
deleted file mode 100644
index 22ba9d5789..0000000000
--- a/osu.Game/Beatmaps/RealmBeatmapCollection.cs
+++ /dev/null
@@ -1,40 +0,0 @@
-// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
-// See the LICENCE file in the repository root for full licence text.
-
-using System;
-using System.Collections.Generic;
-using JetBrains.Annotations;
-using osu.Game.Database;
-using Realms;
-
-namespace osu.Game.Beatmaps
-{
-    public class RealmBeatmapCollection : RealmObject, IHasGuidPrimaryKey
-    {
-        [PrimaryKey]
-        public Guid ID { get; }
-
-        public string Name { get; set; } = string.Empty;
-
-        public IList<string> BeatmapMD5Hashes { get; } = null!;
-
-        /// <summary>
-        /// The date when this collection was last modified.
-        /// </summary>
-        public DateTimeOffset LastModified { get; set; }
-
-        public RealmBeatmapCollection(string? name = null, IList<string>? beatmapMD5Hashes = null)
-        {
-            ID = Guid.NewGuid();
-            Name = name ?? string.Empty;
-            BeatmapMD5Hashes = beatmapMD5Hashes ?? new List<string>();
-
-            LastModified = DateTimeOffset.UtcNow;
-        }
-
-        [UsedImplicitly]
-        private RealmBeatmapCollection()
-        {
-        }
-    }
-}
diff --git a/osu.Game/Collections/BeatmapCollection.cs b/osu.Game/Collections/BeatmapCollection.cs
index abfd0e6dd0..2ffe17d9e6 100644
--- a/osu.Game/Collections/BeatmapCollection.cs
+++ b/osu.Game/Collections/BeatmapCollection.cs
@@ -1,32 +1,50 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using System;
-using osu.Framework.Bindables;
+using System.Collections.Generic;
+using JetBrains.Annotations;
 using osu.Game.Beatmaps;
+using osu.Game.Database;
+using Realms;
 
 namespace osu.Game.Collections
 {
     /// <summary>
     /// A collection of beatmaps grouped by a name.
     /// </summary>
-    public class BeatmapCollection
+    public class BeatmapCollection : RealmObject, IHasGuidPrimaryKey
     {
+        [PrimaryKey]
+        public Guid ID { get; set; }
+
         /// <summary>
         /// The collection's name.
         /// </summary>
-        public readonly Bindable<string> Name = new Bindable<string>();
+        public string Name { get; set; } = string.Empty;
 
         /// <summary>
         /// The <see cref="BeatmapInfo.MD5Hash"/>es of beatmaps contained by the collection.
         /// </summary>
-        public readonly BindableList<string> BeatmapHashes = new BindableList<string>();
+        public IList<string> BeatmapMD5Hashes { get; } = null!;
 
         /// <summary>
         /// The date when this collection was last modified.
         /// </summary>
-        public DateTimeOffset LastModifyDate { get; private set; } = DateTimeOffset.UtcNow;
+        public DateTimeOffset LastModified { get; set; }
+
+        public BeatmapCollection(string? name = null, IList<string>? beatmapMD5Hashes = null)
+        {
+            ID = Guid.NewGuid();
+            Name = name ?? string.Empty;
+            BeatmapMD5Hashes = beatmapMD5Hashes ?? new List<string>();
+
+            LastModified = DateTimeOffset.UtcNow;
+        }
+
+        [UsedImplicitly]
+        private BeatmapCollection()
+        {
+        }
     }
 }
diff --git a/osu.Game/Collections/CollectionFilterDropdown.cs b/osu.Game/Collections/CollectionFilterDropdown.cs
index ed2c0c7cfb..1315cebc8b 100644
--- a/osu.Game/Collections/CollectionFilterDropdown.cs
+++ b/osu.Game/Collections/CollectionFilterDropdown.cs
@@ -1,12 +1,10 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
+using System;
 using System.Collections.Specialized;
 using System.Diagnostics;
 using System.Linq;
-using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
@@ -15,6 +13,7 @@ using osu.Framework.Graphics.UserInterface;
 using osu.Framework.Input.Events;
 using osu.Framework.Localisation;
 using osu.Game.Beatmaps;
+using osu.Game.Database;
 using osu.Game.Graphics.Containers;
 using osu.Game.Graphics.UserInterface;
 using osuTK;
@@ -43,8 +42,8 @@ namespace osu.Game.Collections
         private readonly IBindableList<string> beatmaps = new BindableList<string>();
         private readonly BindableList<CollectionFilterMenuItem> filters = new BindableList<CollectionFilterMenuItem>();
 
-        [Resolved(CanBeNull = true)]
-        private ManageCollectionsDialog manageCollectionsDialog { get; set; }
+        [Resolved]
+        private ManageCollectionsDialog? manageCollectionsDialog { get; set; }
 
         public CollectionFilterDropdown()
         {
@@ -81,7 +80,7 @@ namespace osu.Game.Collections
             if (ShowManageCollectionsItem)
                 filters.Add(new ManageCollectionsFilterMenuItem());
 
-            Current.Value = filters.SingleOrDefault(f => f.Collection != null && f.Collection == selectedItem) ?? filters[0];
+            Current.Value = filters.SingleOrDefault(f => f.Collection != null && f.Collection.ID == selectedItem?.ID) ?? filters[0];
         }
 
         /// <summary>
@@ -92,11 +91,12 @@ namespace osu.Game.Collections
             // Binding the beatmaps will trigger a collection change event, which results in an infinite-loop. This is rebound later, when it's safe to do so.
             beatmaps.CollectionChanged -= filterBeatmapsChanged;
 
-            if (filter.OldValue?.Collection != null)
-                beatmaps.UnbindFrom(filter.OldValue.Collection.BeatmapHashes);
-
-            if (filter.NewValue?.Collection != null)
-                beatmaps.BindTo(filter.NewValue.Collection.BeatmapHashes);
+            // TODO: binding with realm
+            // if (filter.OldValue?.Collection != null)
+            //     beatmaps.UnbindFrom(filter.OldValue.Collection.BeatmapMD5Hashes);
+            //
+            // if (filter.NewValue?.Collection != null)
+            //     beatmaps.BindTo(filter.NewValue.Collection.BeatmapMD5Hashes);
 
             beatmaps.CollectionChanged += filterBeatmapsChanged;
 
@@ -187,26 +187,24 @@ namespace osu.Game.Collections
 
         protected class CollectionDropdownMenuItem : OsuDropdownMenu.DrawableOsuDropdownMenuItem
         {
-            [NotNull]
             protected new CollectionFilterMenuItem Item => ((DropdownMenuItem<CollectionFilterMenuItem>)base.Item).Value;
 
             [Resolved]
-            private IBindable<WorkingBeatmap> beatmap { get; set; }
+            private IBindable<WorkingBeatmap> beatmap { get; set; } = null!;
 
-            [CanBeNull]
-            private readonly BindableList<string> collectionBeatmaps;
-
-            [NotNull]
             private readonly Bindable<string> collectionName;
 
-            private IconButton addOrRemoveButton;
-            private Content content;
+            private IconButton addOrRemoveButton = null!;
+            private Content content = null!;
             private bool beatmapInCollection;
 
+            private IDisposable? realmSubscription;
+
+            private BeatmapCollection? collection => Item.Collection;
+
             public CollectionDropdownMenuItem(MenuItem item)
                 : base(item)
             {
-                collectionBeatmaps = Item.Collection?.BeatmapHashes.GetBoundCopy();
                 collectionName = Item.CollectionName.GetBoundCopy();
             }
 
@@ -223,14 +221,17 @@ namespace osu.Game.Collections
                 });
             }
 
+            [Resolved]
+            private RealmAccess realm { get; set; } = null!;
+
             protected override void LoadComplete()
             {
                 base.LoadComplete();
 
-                if (collectionBeatmaps != null)
+                if (Item.Collection != null)
                 {
-                    collectionBeatmaps.CollectionChanged += (_, _) => collectionChanged();
-                    beatmap.BindValueChanged(_ => collectionChanged(), true);
+                    realmSubscription = realm.SubscribeToPropertyChanged(r => r.Find<BeatmapCollection>(Item.Collection.ID), c => c.BeatmapMD5Hashes, _ => hashesChanged());
+                    beatmap.BindValueChanged(_ => hashesChanged(), true);
                 }
 
                 // Although the DrawableMenuItem binds to value changes of the item's text, the item is an internal implementation detail of Dropdown that has no knowledge
@@ -252,11 +253,11 @@ namespace osu.Game.Collections
                 base.OnHoverLost(e);
             }
 
-            private void collectionChanged()
+            private void hashesChanged()
             {
-                Debug.Assert(collectionBeatmaps != null);
+                Debug.Assert(collection != null);
 
-                beatmapInCollection = collectionBeatmaps.Contains(beatmap.Value.BeatmapInfo.MD5Hash);
+                beatmapInCollection = collection.BeatmapMD5Hashes.Contains(beatmap.Value.BeatmapInfo.MD5Hash);
 
                 addOrRemoveButton.Enabled.Value = !beatmap.IsDefault;
                 addOrRemoveButton.Icon = beatmapInCollection ? FontAwesome.Solid.MinusSquare : FontAwesome.Solid.PlusSquare;
@@ -273,7 +274,7 @@ namespace osu.Game.Collections
 
             private void updateButtonVisibility()
             {
-                if (collectionBeatmaps == null)
+                if (collection == null)
                     addOrRemoveButton.Alpha = 0;
                 else
                     addOrRemoveButton.Alpha = IsHovered || IsPreSelected || beatmapInCollection ? 1 : 0;
@@ -281,13 +282,22 @@ namespace osu.Game.Collections
 
             private void addOrRemove()
             {
-                Debug.Assert(collectionBeatmaps != null);
+                Debug.Assert(collection != null);
 
-                if (!collectionBeatmaps.Remove(beatmap.Value.BeatmapInfo.MD5Hash))
-                    collectionBeatmaps.Add(beatmap.Value.BeatmapInfo.MD5Hash);
+                realm.Write(r =>
+                {
+                    if (!collection.BeatmapMD5Hashes.Remove(beatmap.Value.BeatmapInfo.MD5Hash))
+                        collection.BeatmapMD5Hashes.Add(beatmap.Value.BeatmapInfo.MD5Hash);
+                });
             }
 
             protected override Drawable CreateContent() => content = (Content)base.CreateContent();
+
+            protected override void Dispose(bool isDisposing)
+            {
+                base.Dispose(isDisposing);
+                realmSubscription?.Dispose();
+            }
         }
     }
 }
diff --git a/osu.Game/Collections/CollectionFilterMenuItem.cs b/osu.Game/Collections/CollectionFilterMenuItem.cs
index 031f05c0b4..4c132ba7b7 100644
--- a/osu.Game/Collections/CollectionFilterMenuItem.cs
+++ b/osu.Game/Collections/CollectionFilterMenuItem.cs
@@ -1,10 +1,7 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using System;
-using JetBrains.Annotations;
 using osu.Framework.Bindables;
 
 namespace osu.Game.Collections
@@ -18,26 +15,26 @@ namespace osu.Game.Collections
         /// The collection to filter beatmaps from.
         /// May be null to not filter by collection (include all beatmaps).
         /// </summary>
-        [CanBeNull]
-        public readonly BeatmapCollection Collection;
+        public readonly BeatmapCollection? Collection;
 
         /// <summary>
         /// The name of the collection.
         /// </summary>
-        [NotNull]
         public readonly Bindable<string> CollectionName;
 
         /// <summary>
         /// Creates a new <see cref="CollectionFilterMenuItem"/>.
         /// </summary>
         /// <param name="collection">The collection to filter beatmaps from.</param>
-        public CollectionFilterMenuItem([CanBeNull] BeatmapCollection collection)
+        public CollectionFilterMenuItem(BeatmapCollection? collection)
         {
             Collection = collection;
-            CollectionName = Collection?.Name.GetBoundCopy() ?? new Bindable<string>("All beatmaps");
+            CollectionName = new Bindable<string>(collection?.Name ?? "All beatmaps");
         }
 
-        public bool Equals(CollectionFilterMenuItem other)
+        // TODO: track name changes i guess?
+
+        public bool Equals(CollectionFilterMenuItem? other)
         {
             if (other == null)
                 return false;
@@ -45,7 +42,7 @@ namespace osu.Game.Collections
             // collections may have the same name, so compare first on reference equality.
             // this relies on the assumption that only one instance of the BeatmapCollection exists game-wide, managed by CollectionManager.
             if (Collection != null)
-                return Collection == other.Collection;
+                return Collection.ID == other.Collection?.ID;
 
             // fallback to name-based comparison.
             // this is required for special dropdown items which don't have a collection (all beatmaps / manage collections items below).
diff --git a/osu.Game/Collections/CollectionToggleMenuItem.cs b/osu.Game/Collections/CollectionToggleMenuItem.cs
index 632249913d..8c0e3c587b 100644
--- a/osu.Game/Collections/CollectionToggleMenuItem.cs
+++ b/osu.Game/Collections/CollectionToggleMenuItem.cs
@@ -8,7 +8,7 @@ namespace osu.Game.Collections
 {
     public class CollectionToggleMenuItem : ToggleMenuItem
     {
-        public CollectionToggleMenuItem(RealmBeatmapCollection collection, IBeatmapInfo beatmap)
+        public CollectionToggleMenuItem(BeatmapCollection collection, IBeatmapInfo beatmap)
             : base(collection.Name, MenuItemType.Standard, state =>
             {
                 if (state)
diff --git a/osu.Game/Collections/DeleteCollectionDialog.cs b/osu.Game/Collections/DeleteCollectionDialog.cs
index 33c2174623..7594978870 100644
--- a/osu.Game/Collections/DeleteCollectionDialog.cs
+++ b/osu.Game/Collections/DeleteCollectionDialog.cs
@@ -1,19 +1,16 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using System;
 using Humanizer;
 using osu.Framework.Graphics.Sprites;
-using osu.Game.Beatmaps;
 using osu.Game.Overlays.Dialog;
 
 namespace osu.Game.Collections
 {
     public class DeleteCollectionDialog : PopupDialog
     {
-        public DeleteCollectionDialog(RealmBeatmapCollection collection, Action deleteAction)
+        public DeleteCollectionDialog(BeatmapCollection collection, Action deleteAction)
         {
             HeaderText = "Confirm deletion of";
             BodyText = $"{collection.Name} ({"beatmap".ToQuantity(collection.BeatmapMD5Hashes.Count)})";
diff --git a/osu.Game/Collections/DrawableCollectionList.cs b/osu.Game/Collections/DrawableCollectionList.cs
index 63f04641f4..f376d18224 100644
--- a/osu.Game/Collections/DrawableCollectionList.cs
+++ b/osu.Game/Collections/DrawableCollectionList.cs
@@ -1,35 +1,33 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
+using System.Diagnostics;
 using System.Linq;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
-using osu.Game.Beatmaps;
 using osu.Game.Graphics.Containers;
 using osuTK;
 
 namespace osu.Game.Collections
 {
     /// <summary>
-    /// Visualises a list of <see cref="RealmBeatmapCollection"/>s.
+    /// Visualises a list of <see cref="BeatmapCollection"/>s.
     /// </summary>
-    public class DrawableCollectionList : OsuRearrangeableListContainer<RealmBeatmapCollection>
+    public class DrawableCollectionList : OsuRearrangeableListContainer<BeatmapCollection>
     {
-        private Scroll scroll;
+        private Scroll scroll = null!;
 
         protected override ScrollContainer<Drawable> CreateScrollContainer() => scroll = new Scroll();
 
-        protected override FillFlowContainer<RearrangeableListItem<RealmBeatmapCollection>> CreateListFillFlowContainer() => new Flow
+        protected override FillFlowContainer<RearrangeableListItem<BeatmapCollection>> CreateListFillFlowContainer() => new Flow
         {
             DragActive = { BindTarget = DragActive }
         };
 
         // TODO: source from realm
 
-        protected override OsuRearrangeableListItem<RealmBeatmapCollection> CreateOsuDrawable(RealmBeatmapCollection item)
+        protected override OsuRearrangeableListItem<BeatmapCollection> CreateOsuDrawable(BeatmapCollection item)
         {
             if (item.ID == scroll.PlaceholderItem.Model.ID)
                 return scroll.ReplacePlaceholder();
@@ -49,7 +47,7 @@ namespace osu.Game.Collections
             /// <summary>
             /// The currently-displayed placeholder item.
             /// </summary>
-            public DrawableCollectionListItem PlaceholderItem { get; private set; }
+            public DrawableCollectionListItem PlaceholderItem { get; private set; } = null!;
 
             protected override Container<Drawable> Content => content;
             private readonly Container content;
@@ -79,6 +77,7 @@ namespace osu.Game.Collections
                 });
 
                 ReplacePlaceholder();
+                Debug.Assert(PlaceholderItem != null);
             }
 
             protected override void Update()
@@ -98,7 +97,7 @@ namespace osu.Game.Collections
                 var previous = PlaceholderItem;
 
                 placeholderContainer.Clear(false);
-                placeholderContainer.Add(PlaceholderItem = new DrawableCollectionListItem(new RealmBeatmapCollection(), false));
+                placeholderContainer.Add(PlaceholderItem = new DrawableCollectionListItem(new BeatmapCollection(), false));
 
                 return previous;
             }
@@ -107,7 +106,7 @@ namespace osu.Game.Collections
         /// <summary>
         /// The flow of <see cref="DrawableCollectionListItem"/>. Disables layout easing unless a drag is in progress.
         /// </summary>
-        private class Flow : FillFlowContainer<RearrangeableListItem<RealmBeatmapCollection>>
+        private class Flow : FillFlowContainer<RearrangeableListItem<BeatmapCollection>>
         {
             public readonly IBindable<bool> DragActive = new Bindable<bool>();
 
diff --git a/osu.Game/Collections/DrawableCollectionListItem.cs b/osu.Game/Collections/DrawableCollectionListItem.cs
index a29b2ef81c..6093e69deb 100644
--- a/osu.Game/Collections/DrawableCollectionListItem.cs
+++ b/osu.Game/Collections/DrawableCollectionListItem.cs
@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
 using System;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
@@ -12,7 +10,6 @@ using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Shapes;
 using osu.Framework.Graphics.Sprites;
 using osu.Framework.Input.Events;
-using osu.Game.Beatmaps;
 using osu.Game.Database;
 using osu.Game.Graphics;
 using osu.Game.Graphics.Containers;
@@ -24,15 +21,15 @@ using osuTK.Graphics;
 namespace osu.Game.Collections
 {
     /// <summary>
-    /// Visualises a <see cref="RealmBeatmapCollection"/> inside a <see cref="DrawableCollectionList"/>.
+    /// Visualises a <see cref="BeatmapCollection"/> inside a <see cref="DrawableCollectionList"/>.
     /// </summary>
-    public class DrawableCollectionListItem : OsuRearrangeableListItem<RealmBeatmapCollection>
+    public class DrawableCollectionListItem : OsuRearrangeableListItem<BeatmapCollection>
     {
         private const float item_height = 35;
         private const float button_width = item_height * 0.75f;
 
         /// <summary>
-        /// Whether the <see cref="RealmBeatmapCollection"/> currently exists inside realm.
+        /// Whether the <see cref="BeatmapCollection"/> currently exists inside realm.
         /// </summary>
         public IBindable<bool> IsCreated => isCreated;
 
@@ -41,9 +38,9 @@ namespace osu.Game.Collections
         /// <summary>
         /// Creates a new <see cref="DrawableCollectionListItem"/>.
         /// </summary>
-        /// <param name="item">The <see cref="RealmBeatmapCollection"/>.</param>
+        /// <param name="item">The <see cref="BeatmapCollection"/>.</param>
         /// <param name="isCreated">Whether <paramref name="item"/> currently exists inside realm.</param>
-        public DrawableCollectionListItem(RealmBeatmapCollection item, bool isCreated)
+        public DrawableCollectionListItem(BeatmapCollection item, bool isCreated)
             : base(item)
         {
             this.isCreated.Value = isCreated;
@@ -63,12 +60,15 @@ namespace osu.Game.Collections
         {
             public readonly Bindable<bool> IsCreated = new Bindable<bool>();
 
-            private readonly RealmBeatmapCollection collection;
+            private readonly BeatmapCollection collection;
 
-            private Container textBoxPaddingContainer;
-            private ItemTextBox textBox;
+            private Container textBoxPaddingContainer = null!;
+            private ItemTextBox textBox = null!;
 
-            public ItemContent(RealmBeatmapCollection collection)
+            [Resolved]
+            private RealmAccess realm { get; set; } = null!;
+
+            public ItemContent(BeatmapCollection collection)
             {
                 this.collection = collection;
 
@@ -107,9 +107,6 @@ namespace osu.Game.Collections
                 };
             }
 
-            [Resolved]
-            private RealmAccess realm { get; set; }
-
             protected override void LoadComplete()
             {
                 base.LoadComplete();
@@ -156,20 +153,20 @@ namespace osu.Game.Collections
         {
             public readonly IBindable<bool> IsCreated = new Bindable<bool>();
 
-            public Func<Vector2, bool> IsTextBoxHovered;
-
-            [Resolved(CanBeNull = true)]
-            private IDialogOverlay dialogOverlay { get; set; }
+            public Func<Vector2, bool> IsTextBoxHovered = null!;
 
             [Resolved]
-            private RealmAccess realmAccess { get; set; }
+            private IDialogOverlay? dialogOverlay { get; set; }
 
-            private readonly RealmBeatmapCollection collection;
+            [Resolved]
+            private RealmAccess realmAccess { get; set; } = null!;
 
-            private Drawable fadeContainer;
-            private Drawable background;
+            private readonly BeatmapCollection collection;
 
-            public DeleteButton(RealmBeatmapCollection collection)
+            private Drawable fadeContainer = null!;
+            private Drawable background = null!;
+
+            public DeleteButton(BeatmapCollection collection)
             {
                 this.collection = collection;
                 RelativeSizeAxes = Axes.Y;
diff --git a/osu.Game/Database/LegacyCollectionImporter.cs b/osu.Game/Database/LegacyCollectionImporter.cs
index aa98c491b1..bd32b8c446 100644
--- a/osu.Game/Database/LegacyCollectionImporter.cs
+++ b/osu.Game/Database/LegacyCollectionImporter.cs
@@ -7,7 +7,7 @@ using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
 using osu.Framework.Logging;
-using osu.Game.Beatmaps;
+using osu.Game.Collections;
 using osu.Game.IO;
 using osu.Game.IO.Legacy;
 using osu.Game.Overlays.Notifications;
@@ -75,7 +75,7 @@ namespace osu.Game.Database
             notification.State = ProgressNotificationState.Completed;
         }
 
-        private Task importCollections(List<RealmBeatmapCollection> newCollections)
+        private Task importCollections(List<BeatmapCollection> newCollections)
         {
             var tcs = new TaskCompletionSource<bool>();
 
@@ -85,7 +85,7 @@ namespace osu.Game.Database
                 {
                     foreach (var collection in newCollections)
                     {
-                        var existing = r.All<RealmBeatmapCollection>().FirstOrDefault(c => c.Name == collection.Name);
+                        var existing = r.All<BeatmapCollection>().FirstOrDefault(c => c.Name == collection.Name);
 
                         if (existing != null)
                         {
@@ -111,7 +111,7 @@ namespace osu.Game.Database
             return tcs.Task;
         }
 
-        private List<RealmBeatmapCollection> readCollections(Stream stream, ProgressNotification? notification = null)
+        private List<BeatmapCollection> readCollections(Stream stream, ProgressNotification? notification = null)
         {
             if (notification != null)
             {
@@ -119,7 +119,7 @@ namespace osu.Game.Database
                 notification.Progress = 0;
             }
 
-            var result = new List<RealmBeatmapCollection>();
+            var result = new List<BeatmapCollection>();
 
             try
             {
@@ -135,7 +135,7 @@ namespace osu.Game.Database
                         if (notification?.CancellationToken.IsCancellationRequested == true)
                             return result;
 
-                        var collection = new RealmBeatmapCollection(sr.ReadString());
+                        var collection = new BeatmapCollection(sr.ReadString());
                         int mapCount = sr.ReadInt32();
 
                         for (int j = 0; j < mapCount; j++)
diff --git a/osu.Game/Overlays/Music/Playlist.cs b/osu.Game/Overlays/Music/Playlist.cs
index 954c4de493..19b1b3f84e 100644
--- a/osu.Game/Overlays/Music/Playlist.cs
+++ b/osu.Game/Overlays/Music/Playlist.cs
@@ -38,7 +38,7 @@ namespace osu.Game.Overlays.Music
                 else
                 {
                     item.InSelectedCollection = item.Model.Value.Beatmaps.Select(b => b.MD5Hash)
-                                                    .Any(criteria.Collection.BeatmapHashes.Contains);
+                                                    .Any(criteria.Collection.BeatmapMD5Hashes.Contains);
                 }
             }
 
diff --git a/osu.Game/Overlays/Settings/Sections/Maintenance/CollectionsSettings.cs b/osu.Game/Overlays/Settings/Sections/Maintenance/CollectionsSettings.cs
index 0b17ab9c6c..498859db46 100644
--- a/osu.Game/Overlays/Settings/Sections/Maintenance/CollectionsSettings.cs
+++ b/osu.Game/Overlays/Settings/Sections/Maintenance/CollectionsSettings.cs
@@ -3,7 +3,7 @@
 
 using osu.Framework.Allocation;
 using osu.Framework.Localisation;
-using osu.Game.Beatmaps;
+using osu.Game.Collections;
 using osu.Game.Database;
 using osu.Game.Localisation;
 using osu.Game.Overlays.Notifications;
@@ -50,7 +50,7 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
 
         private void deleteAllCollections()
         {
-            realm.Write(r => r.RemoveAll<RealmBeatmapCollection>());
+            realm.Write(r => r.RemoveAll<BeatmapCollection>());
             notificationOverlay.Post(new ProgressCompletionNotification { Text = "Deleted all collections!" });
         }
     }
diff --git a/osu.Game/Screens/OnlinePlay/DrawableRoomPlaylistItem.cs b/osu.Game/Screens/OnlinePlay/DrawableRoomPlaylistItem.cs
index b17c4934cd..0826c4144b 100644
--- a/osu.Game/Screens/OnlinePlay/DrawableRoomPlaylistItem.cs
+++ b/osu.Game/Screens/OnlinePlay/DrawableRoomPlaylistItem.cs
@@ -499,7 +499,7 @@ namespace osu.Game.Screens.OnlinePlay
                 {
                     if (beatmaps.QueryBeatmap(b => b.OnlineID == beatmap.OnlineID) is BeatmapInfo local && !local.BeatmapSet.AsNonNull().DeletePending)
                     {
-                        var collectionItems = realm.Realm.All<RealmBeatmapCollection>().Select(c => new CollectionToggleMenuItem(c, beatmap)).Cast<OsuMenuItem>().ToList();
+                        var collectionItems = realm.Realm.All<BeatmapCollection>().Select(c => new CollectionToggleMenuItem(c, beatmap)).Cast<OsuMenuItem>().ToList();
                         if (manageCollectionsDialog != null)
                             collectionItems.Add(new OsuMenuItem("Manage...", MenuItemType.Standard, manageCollectionsDialog.Show));
 
diff --git a/osu.Game/Screens/Select/Carousel/CarouselBeatmap.cs b/osu.Game/Screens/Select/Carousel/CarouselBeatmap.cs
index 81734745c4..9267434a66 100644
--- a/osu.Game/Screens/Select/Carousel/CarouselBeatmap.cs
+++ b/osu.Game/Screens/Select/Carousel/CarouselBeatmap.cs
@@ -76,7 +76,7 @@ namespace osu.Game.Screens.Select.Carousel
             }
 
             if (match)
-                match &= criteria.Collection?.BeatmapHashes.Contains(BeatmapInfo.MD5Hash) ?? true;
+                match &= criteria.Collection?.BeatmapMD5Hashes.Contains(BeatmapInfo.MD5Hash) ?? true;
 
             if (match && criteria.RulesetCriteria != null)
                 match &= criteria.RulesetCriteria.Matches(BeatmapInfo);
diff --git a/osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmap.cs b/osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmap.cs
index bfc93b34e2..a1c433b440 100644
--- a/osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmap.cs
+++ b/osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmap.cs
@@ -238,7 +238,7 @@ namespace osu.Game.Screens.Select.Carousel
                 if (beatmapInfo.OnlineID > 0 && beatmapOverlay != null)
                     items.Add(new OsuMenuItem("Details...", MenuItemType.Standard, () => beatmapOverlay.FetchAndShowBeatmap(beatmapInfo.OnlineID)));
 
-                var collectionItems = realm.Realm.All<RealmBeatmapCollection>().Select(c => new CollectionToggleMenuItem(c, beatmapInfo)).Cast<OsuMenuItem>().ToList();
+                var collectionItems = realm.Realm.All<BeatmapCollection>().AsEnumerable().Select(c => new CollectionToggleMenuItem(c, beatmapInfo)).Cast<OsuMenuItem>().ToList();
                 if (manageCollectionsDialog != null)
                     collectionItems.Add(new OsuMenuItem("Manage...", MenuItemType.Standard, manageCollectionsDialog.Show));
 
diff --git a/osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmapSet.cs b/osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmapSet.cs
index 3726d955bd..75c9daf1b1 100644
--- a/osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmapSet.cs
+++ b/osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmapSet.cs
@@ -224,7 +224,7 @@ namespace osu.Game.Screens.Select.Carousel
                 if (beatmapSet.OnlineID > 0 && viewDetails != null)
                     items.Add(new OsuMenuItem("Details...", MenuItemType.Standard, () => viewDetails(beatmapSet.OnlineID)));
 
-                var collectionItems = realm.Realm.All<RealmBeatmapCollection>().AsEnumerable().Select(createCollectionMenuItem).ToList();
+                var collectionItems = realm.Realm.All<BeatmapCollection>().AsEnumerable().Select(createCollectionMenuItem).ToList();
                 if (manageCollectionsDialog != null)
                     collectionItems.Add(new OsuMenuItem("Manage...", MenuItemType.Standard, manageCollectionsDialog.Show));
 
@@ -239,7 +239,7 @@ namespace osu.Game.Screens.Select.Carousel
             }
         }
 
-        private MenuItem createCollectionMenuItem(RealmBeatmapCollection collection)
+        private MenuItem createCollectionMenuItem(BeatmapCollection collection)
         {
             Debug.Assert(beatmapSet != null);