diff --git a/Packages/nadena.dev.modular-avatar/Editor/MenuTree.cs b/Packages/nadena.dev.modular-avatar/Editor/MenuTree.cs
new file mode 100644
index 00000000..b775dec6
--- /dev/null
+++ b/Packages/nadena.dev.modular-avatar/Editor/MenuTree.cs
@@ -0,0 +1,74 @@
+using System.Collections.Generic;
+using System.Linq;
+using NUnit.Framework;
+using UnityEngine;
+using VRC.SDK3.Avatars.Components;
+using VRC.SDK3.Avatars.ScriptableObjects;
+using static VRC.SDK3.Avatars.ScriptableObjects.VRCExpressionsMenu;
+using static VRC.SDK3.Avatars.ScriptableObjects.VRCExpressionsMenu.Control;
+
+// ReSharper disable once CheckNamespace
+namespace nadena.dev.modular_avatar.core.editor {
+	public class MenuTree {
+		private VRCAvatarDescriptor _descriptor;
+		private readonly VRCExpressionsMenu _rootMenu;
+		private readonly HashSet<VRCExpressionsMenu> _included;
+		private readonly Dictionary<VRCExpressionsMenu, List<VRCExpressionsMenu>> _childrenMap;
+
+		public MenuTree(VRCAvatarDescriptor descriptor) {
+			this._descriptor = descriptor;
+			this._rootMenu = descriptor.expressionsMenu;
+			this._included = new HashSet<VRCExpressionsMenu>();
+			this._childrenMap = new Dictionary<VRCExpressionsMenu, List<VRCExpressionsMenu>>();
+
+			if (this._rootMenu == null) {
+				this._rootMenu = ScriptableObject.CreateInstance<VRCExpressionsMenu>();
+			}
+
+			this._included.Add(this._rootMenu);
+		}
+
+		public void AvatarsMenuMapping() {
+			if (this._rootMenu == null) return;
+			this.MappingMenu(this._rootMenu);
+		}
+
+		public void AddMenuInstaller(ModularAvatarMenuInstaller installer) {
+			if (installer.menuToAppend == null) return;
+			VRCExpressionsMenu parent = installer.installTargetMenu;
+			if (parent == null) parent = this._rootMenu;
+			this.MappingMenu(installer.menuToAppend, parent);
+		}
+
+		private void MappingMenu(VRCExpressionsMenu root, VRCExpressionsMenu customParent = null) {
+			Queue<VRCExpressionsMenu> queue = new Queue<VRCExpressionsMenu>();
+			queue.Enqueue(root);
+
+			while (queue.Count > 0) {
+				VRCExpressionsMenu parent = queue.Dequeue();
+				IEnumerable<VRCExpressionsMenu> subMenus = GetSubMenus(parent);
+				if (customParent != null) {
+					parent = customParent;
+					customParent = null;
+				}
+				foreach (VRCExpressionsMenu subMenu in subMenus) {
+					if (!this._childrenMap.TryGetValue(parent, out List<VRCExpressionsMenu> children)) {
+						children = new List<VRCExpressionsMenu>();
+						this._childrenMap[parent] = children;
+					}
+
+					children.Add(subMenu);
+					if (this._included.Contains(subMenu)) continue;
+					queue.Enqueue(subMenu);
+					this._included.Add(subMenu);
+				}
+			}
+		}
+
+		private static IEnumerable<VRCExpressionsMenu> GetSubMenus(VRCExpressionsMenu expressionsMenu) {
+			return expressionsMenu.controls
+				.Where(control => control.type == ControlType.SubMenu && control.subMenu != null)
+				.Select(control => control.subMenu);
+		}
+	}
+}
\ No newline at end of file
diff --git a/Packages/nadena.dev.modular-avatar/Editor/MenuTree.cs.meta b/Packages/nadena.dev.modular-avatar/Editor/MenuTree.cs.meta
new file mode 100644
index 00000000..dc5993a1
--- /dev/null
+++ b/Packages/nadena.dev.modular-avatar/Editor/MenuTree.cs.meta
@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: effd4557902f4578af42d3bdfb7f876d
+timeCreated: 1670746991
\ No newline at end of file