diff --git a/Packages/UniGLTF/Runtime/UniHumanoid/HumanoidLoader.cs b/Packages/UniGLTF/Runtime/UniHumanoid/HumanoidLoader.cs
index db3b5329d..d118f2caa 100644
--- a/Packages/UniGLTF/Runtime/UniHumanoid/HumanoidLoader.cs
+++ b/Packages/UniGLTF/Runtime/UniHumanoid/HumanoidLoader.cs
@@ -1,6 +1,8 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading.Tasks;
+using UniGLTF;
 using UniGLTF.Utils;
 using UnityEngine;
 
@@ -51,14 +53,16 @@ namespace UniHumanoid
             x => x);
 
         /// <summary>
-        /// Avatar を保持する既存の Animatorヒエラルキーの Transform を変更したのちに、
-        /// HumanBone のマッピングを流用して、新たな Avatar を作り直す。
-        /// 古い Avatar は破棄する。
+        /// Recreates an animiator's humanoid avatar. 
+        /// The old Avatar is discarded.
         /// </summary>
-        /// <remarks>
-        /// This method runs asynchronously only in play mode.
-        /// </remarks>
-        public static async Awaitable RebuildHumanAvatar(Animator animator)
+        public static void RebuildHumanAvatar(Animator animator)
+        {
+            var task = RebuildHumanAvatarAsync(animator, new ImmediateCaller());
+            task.Wait();
+        }
+
+        public static async Task RebuildHumanAvatarAsync(Animator animator, IAwaitCaller awaitCaller)
         {
             if (animator == null)
             {
@@ -76,19 +80,22 @@ namespace UniHumanoid
             newAvatar.name = "re-created";
 
             // var newAvatar = LoadHumanoidAvatarFromAnimator(animator);
-            // Animator.avatar を代入したときに副作用でTransformが変更されるのを回避するために削除します。
+            // 1. Delete this to avoid changing Transform as a side effect when assigning Animator.avatar.
             if (Application.isPlaying)
             {
                 GameObject.Destroy(animator);
 
+                // https://github.com/vrm-c/UniVRM/pull/2764
+                // Require IAwaitCaller that has NextFrame capability. RuntimeOnlyAwaitCaller etc. not ImmediateCaller.
                 // Else, the following AddComponent call will fail.
-                await Awaitable.NextFrameAsync();
+                await awaitCaller.NextFrame();
             }
             else
             {
                 GameObject.DestroyImmediate(animator);
             }
-            // 新たに AddComponent する
+
+            // 2. Attach a new one
             target.AddComponent<Animator>().avatar = newAvatar;
         }
     }
diff --git a/Packages/VRM/Runtime/SkinnedMeshUtility/VRMBoneNormalizer.cs b/Packages/VRM/Runtime/SkinnedMeshUtility/VRMBoneNormalizer.cs
index 5d0762c06..c03838d28 100644
--- a/Packages/VRM/Runtime/SkinnedMeshUtility/VRMBoneNormalizer.cs
+++ b/Packages/VRM/Runtime/SkinnedMeshUtility/VRMBoneNormalizer.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading.Tasks;
 using UniGLTF;
 using UniGLTF.MeshUtility;
 using UniGLTF.Utils;
@@ -53,10 +54,13 @@ namespace VRM
         /// <param name="go">対象モデルのルート</param>
         /// <param name="forceTPose">強制的にT-Pose化するか</param>
         /// <param name="useCurrentBlendShapeWeight">BlendShape の現状をbakeするか</param>
-        /// <remarks>
-        /// This method runs asynchronously only in play mode.
-        /// </remarks>
-        public static async Awaitable Execute(GameObject go, bool forceTPose, bool useCurrentBlendShapeWeight)
+        public static void Execute(GameObject go, bool forceTPose, bool useCurrentBlendShapeWeight)
+        {
+            var task = ExecuteAsync(go, forceTPose, useCurrentBlendShapeWeight, new ImmediateCaller());
+            task.Wait();
+        }
+
+        public static async Task ExecuteAsync(GameObject go, bool forceTPose, bool useCurrentBlendShapeWeight, IAwaitCaller awaitCaller)
         {
             if (forceTPose)
             {
@@ -86,7 +90,7 @@ namespace VRM
             // 回転とスケールが除去された新しいヒエラルキーからAvatarを作る
             if (go.TryGetComponent<Animator>(out var animator))
             {
-                await HumanoidLoader.RebuildHumanAvatar(animator);
+                await HumanoidLoader.RebuildHumanAvatarAsync(animator, awaitCaller);
             }
         }