diff --git a/Assets/VRM10/Runtime/Components/Vrm10Runtime/Vrm10Runtime.cs b/Assets/VRM10/Runtime/Components/Vrm10Runtime/Vrm10Runtime.cs
index efaefef26..7c1d11a61 100644
--- a/Assets/VRM10/Runtime/Components/Vrm10Runtime/Vrm10Runtime.cs
+++ b/Assets/VRM10/Runtime/Components/Vrm10Runtime/Vrm10Runtime.cs
@@ -1,5 +1,7 @@
 using System;
+using System.Collections.Generic;
 using System.Linq;
+using UniGLTF;
 using UnityEngine;
 using UniVRM10.FastSpringBones.Blittables;
 using UniVRM10.FastSpringBones.System;
@@ -15,6 +17,7 @@ namespace UniVRM10
         private readonly IVrm10Constraint[] m_constraints;
         private readonly Transform m_head;
         private readonly FastSpringBoneService m_fastSpringBoneService;
+        private readonly Dictionary<Transform, (Vector3 position, Quaternion rotation)> m_defaultTransformStates;
 
         private FastSpringBoneBuffer m_fastSpringBoneBuffer;
 
@@ -47,6 +50,18 @@ namespace UniVRM10
                 // for UnitTest
                 return;
             }
+            
+            var instance = target.GetComponent<RuntimeGltfInstance>();
+            if (instance != null)
+            {
+                // ランタイムインポートならここに到達してほぼゼロコストになる
+                m_defaultTransformStates = instance.Nodes.ToDictionary(tf=> tf, tf=>(tf.position, tf.rotation));
+            }
+            else
+            {
+                // エディタでプレハブ配置してる奴ならこっちに到達して収集する
+                m_defaultTransformStates = target.GetComponentsInChildren<Transform>().ToDictionary(tf=> tf, tf=>(tf.position, tf.rotation));
+            }
 
             m_fastSpringBoneService = FastSpringBoneService.Instance;
             m_fastSpringBoneBuffer = CreateFastSpringBoneBuffer(m_target.SpringBone);
@@ -97,11 +112,21 @@ namespace UniVRM10
                             gravityDir = joint.m_gravityDir,
                             gravityPower = joint.m_gravityPower,
                             stiffnessForce = joint.m_stiffnessForce
-                        }
+                        },
+                        DefaultLocalRotation = GetOrAddDefaultTransformState(joint.transform).rotation
                     }).ToArray(),
                 }).ToArray());
         }
 
+        private (Vector3 position, Quaternion rotation) GetOrAddDefaultTransformState(Transform tf)
+        {
+            if (m_defaultTransformStates.TryGetValue(tf, out var defaultTransformState))
+            {
+                return defaultTransformState;
+            }
+            return m_defaultTransformStates[tf] = (tf.position, tf.rotation);
+        }
+
         private static BlittableColliderType TranslateColliderType(VRM10SpringBoneColliderTypes colliderType)
         {
             switch (colliderType)
diff --git a/Assets/VRM10/Runtime/FastSpringBone/InputPorts/FastSpringBoneBuffer.cs b/Assets/VRM10/Runtime/FastSpringBone/InputPorts/FastSpringBoneBuffer.cs
index 84186af62..89df4753b 100644
--- a/Assets/VRM10/Runtime/FastSpringBone/InputPorts/FastSpringBoneBuffer.cs
+++ b/Assets/VRM10/Runtime/FastSpringBone/InputPorts/FastSpringBoneBuffer.cs
@@ -108,7 +108,7 @@ namespace UniVRM10.FastSpringBones.System
                         parentTransformIndex = parent != null ? transformIndexDictionary[parent] : -1,
                         currentTail = currentTail,
                         prevTail = currentTail,
-                        localRotation = joint.Transform.localRotation,
+                        localRotation = joint.DefaultLocalRotation,
                         boneAxis = localChildPosition.normalized,
                         length = localChildPosition.magnitude
                     });
diff --git a/Assets/VRM10/Runtime/FastSpringBone/InputPorts/FastSpringBoneJoint.cs b/Assets/VRM10/Runtime/FastSpringBone/InputPorts/FastSpringBoneJoint.cs
index 7aff7cf71..98d1a8e65 100644
--- a/Assets/VRM10/Runtime/FastSpringBone/InputPorts/FastSpringBoneJoint.cs
+++ b/Assets/VRM10/Runtime/FastSpringBone/InputPorts/FastSpringBoneJoint.cs
@@ -9,5 +9,6 @@ namespace UniVRM10.FastSpringBones.System
     {
         public Transform Transform;
         public BlittableJoint Joint;
+        public Quaternion DefaultLocalRotation;
     }
 }
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