diff --git a/osu.Game/Rulesets/Objects/Pooling/HitObjectEntryManager.cs b/osu.Game/Rulesets/Objects/Pooling/HitObjectEntryManager.cs
index f14f8b6f61..71c0a88616 100644
--- a/osu.Game/Rulesets/Objects/Pooling/HitObjectEntryManager.cs
+++ b/osu.Game/Rulesets/Objects/Pooling/HitObjectEntryManager.cs
@@ -19,13 +19,38 @@ namespace osu.Game.Rulesets.Objects.Pooling
         /// </summary>
         public IEnumerable<HitObjectLifetimeEntry> AllEntries => entryMap.Values;
 
+        /// <summary>
+        /// Invoked when a new <see cref="HitObjectLifetimeEntry"/> is added to this <see cref="HitObjectEntryManager"/>..
+        /// The second parameter of the event is the parent hit object.
+        /// </summary>
         public event Action<HitObjectLifetimeEntry, HitObject?>? OnEntryAdded;
+
+        /// <summary>
+        /// Invoked when a <see cref="HitObjectLifetimeEntry"/> is removed from this <see cref="HitObjectEntryManager"/>.
+        /// The second parameter of the event is the parent hit object.
+        /// </summary>
         public event Action<HitObjectLifetimeEntry, HitObject?>? OnEntryRemoved;
 
         private readonly Func<HitObject, HitObjectLifetimeEntry> createLifetimeEntry;
 
+        /// <summary>
+        /// Provides the reverse mapping of <see cref="HitObjectLifetimeEntry.HitObject"/> for each entry.
+        /// </summary>
         private readonly Dictionary<HitObject, HitObjectLifetimeEntry> entryMap = new Dictionary<HitObject, HitObjectLifetimeEntry>();
+
+        /// <summary>
+        /// Stores the parent hit object for entries of the nested hit objects.
+        /// A <c>null</c> is stored for entries of the top-level hit objects.
+        /// </summary>
+        /// <remarks>
+        /// The parent hit object of a pooled hit object may be non-pooled.
+        /// In that case, no corresponding <see cref="HitObjectLifetimeEntry"/> is stored in this <see cref="HitObjectEntryManager"/>.
+        /// </remarks>
         private readonly Dictionary<HitObjectLifetimeEntry, HitObject?> parentMap = new Dictionary<HitObjectLifetimeEntry, HitObject?>();
+
+        /// <summary>
+        /// Stores the list of entries managed by this <see cref="HitObjectEntryManager"/> for each hit object managed by this <see cref="HitObjectEntryManager"/>.
+        /// </summary>
         private readonly Dictionary<HitObject, List<HitObjectLifetimeEntry>> childrenMap = new Dictionary<HitObject, List<HitObjectLifetimeEntry>>();
 
         public HitObjectEntryManager(Func<HitObject, HitObjectLifetimeEntry> createLifetimeEntry)