diff --git a/packages/stage-ui/src/components/Scenarios/Settings/ModelSettings/VRM.vue b/packages/stage-ui/src/components/Scenarios/Settings/ModelSettings/VRM.vue
index 209275374..e0680ebe4 100644
--- a/packages/stage-ui/src/components/Scenarios/Settings/ModelSettings/VRM.vue
+++ b/packages/stage-ui/src/components/Scenarios/Settings/ModelSettings/VRM.vue
@@ -43,7 +43,6 @@ const {
 
   envSelect,
   skyBoxIntensity,
-  specularMix,
 } = storeToRefs(vrm)
 const trackingOptions = computed(() => [
   { value: 'camera', label: t('settings.vrm.scale-and-position.eye-tracking-mode.options.option.camera'), class: 'col-start-3' },
@@ -202,14 +201,9 @@ const tabList = [
             <div grid="~ cols-5 gap-1" p-2>
               <PropertyNumber
                 v-model="skyBoxIntensity"
-                :config="{ min: 0, max: 2, step: 0.01, label: 'Intensity' }"
+                :config="{ min: 0, max: 1, step: 0.01, label: 'Intensity' }"
                 :label="t('settings.vrm.skybox.skybox-intensity')"
               />
-              <PropertyNumber
-                v-model="specularMix"
-                :config="{ min: 0, max: 1, step: 0.01, label: 'Mix' }"
-                :label="t('settings.vrm.skybox.skybox-specular-mix')"
-              />
             </div>
           </div>
         </template>
diff --git a/packages/stage-ui/src/components/Scenes/VRM/Model.vue b/packages/stage-ui/src/components/Scenes/VRM/Model.vue
index 43b55e395..f52ad298f 100644
--- a/packages/stage-ui/src/components/Scenes/VRM/Model.vue
+++ b/packages/stage-ui/src/components/Scenes/VRM/Model.vue
@@ -1,7 +1,7 @@
 <script setup lang="ts">
-/* eslint-disable style/max-statements-per-line */
 import type { VRMCore } from '@pixiv/three-vrm-core'
-import type { AnimationClip, Group, Material, SphericalHarmonics3, Texture } from 'three'
+import type { AnimationClip, Group, SphericalHarmonics3, Texture } from 'three'
+import type * as THREE from 'three'
 
 import { VRMUtils } from '@pixiv/three-vrm'
 import { useLoop, useTresContext } from '@tresjs/core'
@@ -11,13 +11,9 @@ import {
   AnimationMixer,
   MathUtils,
   Mesh,
-  MeshBasicMaterial,
   MeshPhysicalMaterial,
   MeshStandardMaterial,
-  MeshToonMaterial,
   Quaternion,
-  RawShaderMaterial,
-  ShaderMaterial,
   SRGBColorSpace,
   Vector3,
   VectorKeyframeTrack,
@@ -27,6 +23,12 @@ import { computed, onMounted, onUnmounted, ref, toRef, watch } from 'vue'
 import { clipFromVRMAnimation, loadVRMAnimation, useBlink, useIdleEyeSaccades } from '../../../composables/vrm/animation'
 import { loadVrm } from '../../../composables/vrm/core'
 import { useVRMEmote } from '../../../composables/vrm/expression'
+import {
+  createIblProbeController,
+  injectDiffuseIBL,
+  normalizeEnvMode,
+  updateNprShaderSetting,
+} from '../../../composables/vrm/shader/ibl'
 import { useVRM } from '../../../stores/vrm'
 
 const props = defineProps<{
@@ -69,7 +71,6 @@ const {
   trackingMode,
 
   envSelect,
-  specularMix,
   skyBoxIntensity,
 } = storeToRefs(vrmStore)
 const vrmGroup = ref<Group>()
@@ -77,52 +78,8 @@ const idleEyeSaccades = useIdleEyeSaccades()
 
 const nprProgramVersion = ref(0)
 
-// Try the best to extract the matcap texture from various possible places
-// TODO: this function should be refactored and moved to composables/vrm
-function extractMatcapTexture(mat: any): Texture | null {
-  // a) MeshMatcapMaterial
-  if ('matcap' in mat && mat.matcap)
-    return mat.matcap as Texture
-
-  // b) For common MToon materials, it might be under uniforms
-  const u = (mat as any).uniforms
-  if (u) {
-    // try different possible names...
-    if (u.matcapTexture?.value)
-      return u.matcapTexture.value as Texture
-    if (u.sphereAddTexture?.value)
-      return u.sphereAddTexture.value as Texture
-    if (u._MatCapTex?.value)
-      return u._MatCapTex.value as Texture
-    if (u._SphereAdd?.value)
-      return u._SphereAdd.value as Texture
-  }
-
-  // c) If the matcap is in the gltf extension
-  const ud = (mat as any).userData || {}
-  const ext = ud.gltfExtensions?.VRMC_materials_mtoon || ud.vrmMaterialProperties || ud.mtoon
-  if (ext) {
-    // Different possible names...
-    const cand
-      = ext.matcapTexture
-        || ext.sphereAddTexture
-        || ext.matcap
-        || ext.sphereAdd
-    if (cand && cand.isTexture)
-      return cand as Texture
-  }
-
-  return null
-}
-
-// flaten the irrSH to array of Vector3
-function shToVec3Array(sh: SphericalHarmonics3 | null): Vector3[] {
-  const arr: Vector3[] = Array.from({ length: 9 }, () => new Vector3())
-  if (!sh)
-    return arr
-  for (let i = 0; i < 9; i++) arr[i].copy(sh.coefficients[i])
-  return arr
-}
+// For MToon IBL
+let airiIblProbe: ReturnType<typeof createIblProbeController> | null = null
 
 async function loadModel() {
   await until(modelLoading).not.toBeTruthy()
@@ -257,264 +214,58 @@ async function loadModel() {
 
       vrmEmote.value = useVRMEmote(_vrm)
 
-      // TODO: perhaps we should allow user to choose whether to enable
-      //       this kind of behavior or not?
-      // - Lilia: NO need, cause NPR mat should always follow NPR route, and BPR mat shoule always follow PBR route.
-      // WORKAROUND: set to use envMapIntensity for all matched materials
-      // - Lilia: YES, envMapIntensity will be exposed to GUI user to adjust.
-      // REVIEW: MeshToonMaterial, and MeshBasicMaterial will not be affected
-      //         since they do not have envMapIntensity property
-      // - Lilia: NPR mat can be affected by envMapIntensity if we choose to user skybox as envMap
-      //        This part will be implemented as a NPR HDRI shader injection
+      // material selection
+      function isMToon(mat: any): boolean {
+        return !!(mat?.isShaderMaterial && mat.userData?.vrmMaterialType === 'MToon'
+        )
+      }
+      const isShaderMat = (m: any): m is THREE.ShaderMaterial => !!m?.isShaderMaterial
+
+      // refactoring
+      // MToon material skybox lightProbe setting
+      if (!airiIblProbe && scene.value)
+        airiIblProbe = createIblProbeController(scene.value)
+
+      // Material traverse setting
       _vrm.scene.traverse((child) => {
         if (child instanceof Mesh && child.material) {
           const material = Array.isArray(child.material) ? child.material : [child.material]
           material.forEach((mat) => {
+            // console.debug("shader material: ", mat)
             if (mat instanceof MeshStandardMaterial || mat instanceof MeshPhysicalMaterial) {
               // Should read envMap intensity from outside props
               mat.envMapIntensity = 1.0
               mat.needsUpdate = true
             }
-            else if (
-              mat instanceof MeshToonMaterial
-              || mat instanceof MeshBasicMaterial
-              || mat instanceof ShaderMaterial
-              || mat instanceof RawShaderMaterial
-            ) {
+            else if (isMToon(mat)) {
+              // --- MToon material, add IBL lightProbe only ---
               // close tone mapping for NPR materials
               if ('toneMapped' in mat)
                 mat.toneMapped = false
+            }
+            else if (isShaderMat(mat)) {
+              // --- Shader material, further IBL injection needed ---
               // disable envMap for NPR materials, envMap will be reassigned by default skybox
+              // close tone mapping for NPR materials
+              if ('toneMapped' in mat)
+                mat.toneMapped = false
               if ('envMap' in mat && mat.envMap)
                 mat.envMap = null
               // NPR materials usually use sRGB textures
-              if ('map' in mat && mat.map && 'colorSpace' in mat.map) {
-                // try...catch to avoid some weird error (diff verion of three.js?)
-                try { mat.map.colorSpace = SRGBColorSpace }
-                catch {}
+              const tex = (mat as any).map as THREE.Texture | undefined
+              if (tex && (tex as any).colorSpace !== undefined) {
+                try {
+                  (tex as any).colorSpace = SRGBColorSpace
+                }
+                catch (e) {
+                  console.warn('Failed to set colorSpace on texture:', e)
+                }
               }
 
-              // Foce recompile shader to inject npr env shader at the begining
-              const baseKey = mat.customProgramCacheKey?.() ?? ''
-              mat.customProgramCacheKey = () => `${baseKey}|npr:${nprProgramVersion.value}`
-
-              // NPR shader injection
-              const prevOnBeforeCompile = mat.onBeforeCompile
-              mat.onBeforeCompile = (shader: any, renderer: any) => {
-                // Keep the previous onBeforeCompile behaviour if any
-                prevOnBeforeCompile?.(shader, renderer)
-                // Obtain skybox texture from scene environment
-                const equirectTex = props.nprEquirectTex ?? null
-                // use the type assertion to fix TS error...
-                const m = mat as unknown as Material & {
-                  extensions?: { shaderTextureLOD?: boolean }
-                }
-                m.extensions = { ...(m.extensions || {}), shaderTextureLOD: true }
-                // If matcap texture is available, then use matcap in IBL specular reflection
-                const matcapTex = extractMatcapTexture(mat)
-
-                // If no normal, then skip the rest
-                const hasNormal = shader.fragmentShader.includes('vNormal')
-                if (!hasNormal)
-                  return
-
-                // --- vWorldPos/vWorldNormal ---
-                if (!shader.vertexShader.includes('varying vec3 vWorldPos')) {
-                  shader.vertexShader
-                    = `
-                    varying vec3 vWorldPos;
-                    varying vec3 vWorldNormal;
-                    ${shader.vertexShader}`
-                }
-                if (!shader.fragmentShader.includes('varying vec3 vWorldPos')) {
-                  shader.fragmentShader
-                    = `
-                    varying vec3 vWorldPos;
-                    varying vec3 vWorldNormal;
-                    ${shader.fragmentShader}`
-                }
-
-                // --- vertex shader injection ---
-                shader.vertexShader = shader.vertexShader
-                  .replace(
-                    '#include <defaultnormal_vertex>',
-                    `
-                    #include <defaultnormal_vertex>
-                    vWorldNormal = normalize( mat3( modelMatrix ) * objectNormal );
-                    `,
-                  )
-                  .replace(
-                    '#include <begin_vertex>',
-                    `
-                    #include <begin_vertex>
-                    vWorldPos = ( modelMatrix * vec4( transformed, 1.0 ) ).xyz;
-                    `,
-                  )
-
-                // Setup uniforms
-                shader.uniforms.uNprEnvMode = { value: (envSelect.value === 'hemisphere') ? 0 : 2 } // 0=hemi: no further injection; 2=skybox
-                shader.uniforms.uEnvIntensity = { value: skyBoxIntensity.value } // exposed to GUI
-                shader.uniforms.uEnvMapEquirect = { value: equirectTex }
-                shader.uniforms.uSpecularMix = { value: specularMix.value }
-                // LOD mip
-                shader.uniforms.uEnvMaxMip = { value: 8.0 }
-                shader.uniforms.uBrightMip = { value: 2.0 } // bright color = low mip
-                shader.uniforms.uShadowMip = { value: 8.0 } // shadow color = high mip
-                // Tint
-                // 染色强度控制
-                shader.uniforms.uHighlightTint = { value: 0.6 }
-                shader.uniforms.uShadowTint = { value: 0.35 }
-                // Specular uniforms for NPR skybox
-                shader.uniforms.uSpecToonThreshold = { value: 0.9 } // highlight threshold
-                shader.uniforms.uSpecToonWidth = { value: 0.15 } // highlight width
-                shader.uniforms.uSpecPower = { value: 10.0 } // highlight sharpness
-                shader.uniforms.uSpecMip = { value: 8.0 } // default LOD mip level for specular
-                // Irradiance sampling
-                const emptySH: Vector3[] = Array.from({ length: 9 }, () => new Vector3())
-                shader.uniforms.uSHCoeffs = { value: emptySH }
-                // Specular matcap
-                // shader.uniforms.uUseMatcap         = { value: !!matcapTex }
-                shader.uniforms.uUseMatcap = { value: false }
-                shader.uniforms.uMatcap = { value: matcapTex ?? null }
-                shader.uniforms.uMatcapIntensity = { value: 1.0 }
-
-                // console.debug('same matcap?', matcapTex === shader.uniforms.uMatcap.value)
-
-                // Shader injection!
-                shader.fragmentShader = shader.fragmentShader.replace(
-                  '#include <common>',
-                  `
-                      #include <common>
-                      uniform int   uNprEnvMode;         // 0=off, 2=Skybox
-                      uniform float uEnvIntensity;
-                      uniform float uSpecularMix;       // 0=diffuse only, 1=specular only
-
-                      uniform float uSpecToonThreshold;
-                      uniform float uSpecToonWidth;
-                      uniform float uSpecPower; 
-                      uniform bool  uUseMatcap;
-                      uniform sampler2D uMatcap;
-                      uniform float uMatcapIntensity;
-                      
-                      uniform sampler2D uEnvMapEquirect; // Skybox(equirect)
-
-                      uniform vec3 uSHCoeffs[9];  // for irradiance
-                      uniform float uSpecMip;   // default LOD mip for specular
-
-                      // --- Direction to equirectangular UV ---
-                      vec2 dirToEquirectUV(vec3 d){
-                        d = normalize(d);
-                        float phi = atan(d.z, d.x);
-                        float th  = asin(clamp(d.y, -1.0, 1.0));
-                        return vec2(0.5 + phi/(2.0*PI), 0.5 - th/PI);
-                      }
-
-                      // --- Spherical Harmonics (3rd order) for diffuse IBL ---
-
-                      // Constants for SH basis functions
-                      const float C0 = 1.0 / (2.0 * sqrt(PI));
-                      const float C1 = sqrt(3.0 / PI) / 2.0;
-                      const float C2 = sqrt(15.0 / PI) / 2.0;
-                      const float C3 = sqrt(5.0 / PI) / 4.0;
-                      const float C4 = sqrt(15.0 / PI) / 4.0;
-
-                      vec3 evalIrradianceSH( vec3 n ) {
-                        vec3 sh = vec3(0.0);
-                        sh += uSHCoeffs[0] * C0;
-                        sh += uSHCoeffs[1] * (-C1 * n.y);
-                        sh += uSHCoeffs[2] * ( C1 * n.z);
-                        sh += uSHCoeffs[3] * (-C1 * n.x);
-                        sh += uSHCoeffs[4] * ( C2 * n.x * n.y);
-                        sh += uSHCoeffs[5] * (-C2 * n.y * n.z);
-                        sh += uSHCoeffs[6] * ( C3 * (3.0 * n.z * n.z - 1.0));
-                        sh += uSHCoeffs[7] * (-C2 * n.x * n.z);
-                        sh += uSHCoeffs[8] * ( C4 * (n.x * n.x - n.y * n.y));
-                        return sh;
-                      }
-                      `,
-                ).replace(
-                  '#include <dithering_fragment>',
-                  `
-                      // --- NPR skybox env lighting injection ---
-                      vec3 n = normalize(vNormal);
-                      vec3 nW = inverseTransformDirection(n, viewMatrix);
-
-                      vec3 envCol = vec3(0.0);
-                      if(uNprEnvMode == 2) {
-                        // View direction in world space
-                        #ifdef USE_VIEWPOSITION
-                          vec3 v = normalize(-vViewPosition);
-                          vec3 vW = inverseTransformDirection(v, viewMatrix);
-                        #else
-                          vec3 vW = normalize(-cameraPosition);
-                        #endif
-
-                        // Reflection direction in world space
-                        vec3 rW = reflect(-vW, nW);
-
-                        // To resolve the upside-down reflection issue of equirect map
-                        // nW.y = -nW.y;
-                        // rW.y = -rW.y;                       
-                        
-                        // --- IBL Diffusion ---
-                        // SH-based irradiance
-                        vec3 I = evalIrradianceSH(nW);
-                        vec3 albedo = gl_FragColor.rgb;
-                        // albedo/pi * I(n)
-                        vec3 envDiff = (albedo / 3.14159265) * I * (uEnvIntensity);
-                        // TODO: Tint
-
-                        // --- IBL Specular reflection ---
-                        // TODO: a more stylistic specular reflection model. Is specular necessary?
-                        vec3 envSpec;
-                        if (uUseMatcap) {
-                          // Matcap-based specular
-                          vec3 V = vec3(0.0, 0.0, 1.0);
-                          vec3 nV = n;
-                          vec3 R = reflect(-V, nV);
-                          float m = 2.0 * sqrt( pow(R.x, 2.0) + pow(R.y, 2.0) + pow(R.z + 1.0, 2.0) );
-                          vec2 uvMC = R.xy / m * 0.5 + 0.5;
-                          vec3 matcapCol = texture2D(uMatcap, uvMC).rgb;
-                          envSpec = matcapCol * uMatcapIntensity;
-                        }
-                        else {
-                          // Equirect-based specular, LOD needed for NPR
-                          vec3 N = normalize(vWorldNormal);
-                          vec3 V = normalize(cameraPosition - vWorldPos); // camera to frag
-                          vec3 R = reflect(-V, N);
-                          vec2 uvRef = dirToEquirectUV(R);
-                          #if __VERSION__ >= 300
-                            vec3 envRef = textureLod(uEnvMapEquirect, uvRef, uSpecMip).rgb;
-                          #else
-                            #ifdef GL_EXT_shader_texture_lod
-                              vec3 envRef = texture2DLodEXT(uEnvMapEquirect, uvRef, uSpecMip).rgb;
-                            #else
-                              vec3 envRef = texture2D(uEnvMapEquirect, uvRef).rgb;
-                            #endif
-                          #endif
-                          // Blinn/Phong
-                          float specRaw = clamp(dot(R, V), 0.0, 1.0);
-                          float sToon = smoothstep(uSpecToonThreshold - uSpecToonWidth,
-                                                  uSpecToonThreshold + uSpecToonWidth, specRaw);
-                          envSpec = pow(sToon, uSpecPower) * envRef * uEnvIntensity;
-                        }
-
-                        // Mix specular and diffuse
-                        envCol = mix(envDiff, envSpec, uSpecularMix);
-
-                        // skybox color mixing 
-                        gl_FragColor.rgb += envCol;
-                      }
-                      // --- Injection ends ---
-
-                      #include <dithering_fragment>
-                      `,
-                )
-                mat.userData.__nprUniforms = shader.uniforms
-              }
-              mat.needsUpdate = true
+              // refactoring, IBL injection
+              // TODO: it should be an unified shader injection entrance
+              injectDiffuseIBL(mat)
             }
-            // console.debug('material: ', mat)
           })
         }
       })
@@ -594,59 +345,30 @@ function componentCleanUp() {
   if (vrm.value) {
     vrm.value.scene.removeFromParent()
     VRMUtils.deepDispose(vrm.value.scene)
+    airiIblProbe?.dispose()
   }
 }
 
-// Switch to NPR SkyBox
-function updateNprUniforms(tex: Texture | null, nprIrrSH?: SphericalHarmonics3 | null) {
-  const root = vrm.value?.scene
-  if (!root)
-    return
-
-  const mode = (envSelect.value === 'skyBox' && !!tex) ? 2 : 0 // 0=off，2=skybox
-  root.traverse((child) => {
-    if (child instanceof Mesh && child.material) {
-      const mats = Array.isArray(child.material) ? child.material : [child.material]
-      mats.forEach((mat) => {
-        const u = mat.userData?.__nprUniforms
-        if (!u)
-          return
-        // Skybox texture and mode
-        u.uEnvMapEquirect.value = tex
-        u.uNprEnvMode.value = mode
-        u.uEnvIntensity.value = skyBoxIntensity.value
-        u.uSpecularMix.value = specularMix.value
-        // Update SH coeffs after the skybox is ready
-        if (u.uSHCoeffs && nprIrrSH) {
-          // console.debug('Updating SH coeffs with new props.nprIrrSH:', props.nprIrrSH)
-          const irrSH = shToVec3Array(nprIrrSH)
-          for (let i = 0; i < 9; i++) {
-            u.uSHCoeffs.value[i].copy(irrSH[i])
-          }
-          // console.debug('Updated SH coeffs:', u.uSHCoeffs.value)
-        }
-        // Update LOD max mip based on the texture size when the skybox is ready
-        if (tex?.image?.width && tex?.image?.height) {
-          const maxMip = Math.floor(Math.log2(Math.max(tex.image.width, tex.image.height)))
-          u.uEnvMaxMip.value = maxMip
-          u.uShadowMip.value = maxMip // max mip for shadow tint
-        }
-      })
-    }
-  })
-}
 // watch NPR skybox
 watch(
   () => [
     envSelect.value,
     props.nprEquirectTex,
     skyBoxIntensity.value,
-    specularMix.value,
     props.nprIrrSH,
   ],
   async () => {
+    if (!vrm.value)
+      return
     nprProgramVersion.value += 1
-    updateNprUniforms(props.nprEquirectTex ?? null, props.nprIrrSH ?? null)
+    // updateNprUniforms(props.nprEquirectTex ?? null, props.nprIrrSH ?? null)
+    const mode = normalizeEnvMode(envSelect.value)
+    updateNprShaderSetting(vrm.value?.scene, {
+      mode,
+      intensity: skyBoxIntensity.value,
+      sh: props.nprIrrSH ?? null,
+    })
+    airiIblProbe?.update(mode, skyBoxIntensity.value, props.nprIrrSH ?? null)
   },
   { immediate: true, deep: false },
 )
diff --git a/packages/stage-ui/src/composables/vrm/index.ts b/packages/stage-ui/src/composables/vrm/index.ts
index f73653d09..baf72ab50 100644
--- a/packages/stage-ui/src/composables/vrm/index.ts
+++ b/packages/stage-ui/src/composables/vrm/index.ts
@@ -2,3 +2,4 @@ export * from './animation'
 export * from './core'
 export * from './expression'
 export * from './loader'
+export * from './shader/ibl'
diff --git a/packages/stage-ui/src/composables/vrm/shader/ibl.ts b/packages/stage-ui/src/composables/vrm/shader/ibl.ts
new file mode 100644
index 000000000..cca11c90c
--- /dev/null
+++ b/packages/stage-ui/src/composables/vrm/shader/ibl.ts
@@ -0,0 +1,173 @@
+// stage-ui/composables/shader/ibl.ts
+import * as THREE from 'three'
+
+// ===== head guard shader injection =====
+const VS_DECL = `
+#ifndef AIRI_DIFFUSE_VS_DECL
+#define AIRI_DIFFUSE_VS_DECL
+varying vec3 vWorldNormal;
+#endif
+`
+
+const VS_APPLY = `
+#ifndef AIRI_DIFFUSE_VS_APPLY
+#define AIRI_DIFFUSE_VS_APPLY
+vWorldNormal = normalize( mat3( modelMatrix ) * objectNormal );
+#endif
+`
+
+const FS_COMMON = `
+#ifndef AIRI_DIFFUSE_COMMON
+#define AIRI_DIFFUSE_COMMON
+uniform int   uNprEnvMode;    // 0=off, 2=skybox
+uniform float uEnvIntensity;
+uniform vec3  uSHCoeffs[9];
+varying vec3  vWorldNormal;
+
+// 3rd-order SH constants
+const float C0=0.2820947918; 
+const float C1=0.4886025119;
+const float C2=1.0925484306; 
+const float C3=0.3153915653;
+const float C4=0.5462742153;
+
+vec3 AIRI_evalIrradianceSH(vec3 n){
+  n = normalize(n);
+  vec3 r = uSHCoeffs[0]*C0;
+  r += uSHCoeffs[1]*(-C1*n.y);
+  r += uSHCoeffs[2]*( C1*n.z);
+  r += uSHCoeffs[3]*(-C1*n.x);
+  r += uSHCoeffs[4]*( C2*n.x*n.y);
+  r += uSHCoeffs[5]*(-C2*n.y*n.z);
+  r += uSHCoeffs[6]*( C3*(3.0*n.z*n.z-1.0));
+  r += uSHCoeffs[7]*(-C2*n.x*n.z);
+  r += uSHCoeffs[8]*( C4*(n.x*n.x-n.y*n.y));
+  return r;
+}
+#endif
+`
+
+const FS_APPLY = `
+#ifndef AIRI_DIFFUSE_APPLY
+#define AIRI_DIFFUSE_APPLY
+if (uNprEnvMode == 2) {
+  vec3 I = AIRI_evalIrradianceSH(normalize(vWorldNormal));
+  gl_FragColor.rgb += (gl_FragColor.rgb / PI) * I * uEnvIntensity;
+}
+#endif
+`
+
+// ===== Utility tools =====
+export type EnvMode = 'off' | 'skyBox' | 'hemisphere'
+
+export const isShaderMat = (m: any): m is THREE.ShaderMaterial => !!m?.isShaderMaterial
+export const isRawShader = (m: any): m is THREE.RawShaderMaterial => !!m?.isRawShaderMaterial
+export const isMToon = (mat: any) => !!(mat?.isShaderMaterial && mat.userData?.vrmMaterialType === 'MToon')
+
+export function normalizeEnvMode(v?: string | null): EnvMode {
+  if (v === 'skyBox')
+    return 'skyBox'
+  if (v === 'hemisphere')
+    return 'hemisphere'
+  return 'off'
+}
+
+// Turn SphericalHarmonics3 to vec3[9] uniforms
+function assignSHUniform(u: any, sh: THREE.SphericalHarmonics3 | null | undefined) {
+  if (!u?.uSHCoeffs || !u.uSHCoeffs.value || !Array.isArray(u.uSHCoeffs.value))
+    return
+  if (!sh)
+    return
+  for (let i = 0; i < 9; i++) {
+    u.uSHCoeffs.value[i] ||= new THREE.Vector3()
+    u.uSHCoeffs.value[i].copy(sh.coefficients[i])
+  }
+}
+
+// ===== Shader Material: IBL shader injection =====
+export function injectDiffuseIBL(mat: THREE.ShaderMaterial) {
+  const baseKey = mat.customProgramCacheKey?.() ?? ''
+  mat.customProgramCacheKey = () => `${baseKey}|airi-diffuse-ibl`
+
+  const prev = mat.onBeforeCompile
+  mat.onBeforeCompile = (shader: any, renderer: any) => {
+    prev?.(shader, renderer)
+
+    // vertex shader declare & apply
+    if (!shader.vertexShader.includes('AIRI_DIFFUSE_VS_DECL')) {
+      shader.vertexShader = `${VS_DECL}\n${shader.vertexShader}`
+    }
+    if (shader.vertexShader.includes('#include <defaultnormal_vertex>')
+      && !shader.vertexShader.includes('AIRI_DIFFUSE_VS_APPLY')) {
+      shader.vertexShader = shader.vertexShader.replace(
+        '#include <defaultnormal_vertex>',
+        `#include <defaultnormal_vertex>\n${VS_APPLY}`,
+      )
+    }
+
+    // fragement shader common
+    if (!shader.fragmentShader.includes('AIRI_DIFFUSE_COMMON')) {
+      shader.fragmentShader = shader.fragmentShader.replace(
+        '#include <common>',
+        `#include <common>\n${FS_COMMON}`,
+      )
+    }
+
+    // fragement shader apply
+    if (!shader.fragmentShader.includes('AIRI_DIFFUSE_APPLY')) {
+      shader.fragmentShader = shader.fragmentShader.replace(
+        '#include <dithering_fragment>',
+        `${FS_APPLY}\n#include <dithering_fragment>`,
+      )
+    }
+
+    // uniforms
+    const emptySH = Array.from({ length: 9 }, () => new THREE.Vector3())
+    shader.uniforms.uNprEnvMode ||= { value: 0 }
+    shader.uniforms.uEnvIntensity ||= { value: 0.0 }
+    shader.uniforms.uSHCoeffs ||= { value: emptySH };
+    (mat.userData ||= {}).__airiIbl = shader.uniforms
+  }
+
+  if ('toneMapped' in mat)
+    (mat as any).toneMapped = false
+  mat.needsUpdate = true
+}
+
+// update shader settings
+export function updateNprShaderSetting(
+  root: THREE.Object3D,
+  opts: { mode: EnvMode, intensity: number, sh?: THREE.SphericalHarmonics3 | null },
+) {
+  const shaderMode = opts.mode === 'skyBox' ? 2 : 0
+  root.traverse((o) => {
+    const mesh = o as THREE.Mesh
+    const raw = (mesh as any).material
+    const mats: any[] = raw ? (Array.isArray(raw) ? raw : [raw]) : []
+    mats.forEach((m) => {
+      const u = m?.userData?.__airiIbl
+      if (!u)
+        return
+      u.uNprEnvMode.value = shaderMode
+      u.uEnvIntensity.value = opts.intensity
+      assignSHUniform(u, opts.sh ?? null)
+    })
+  })
+}
+
+// ===== MToon LightProbe IBL =====
+export function createIblProbeController(scene: THREE.Scene) {
+  const probe = new THREE.LightProbe()
+  probe.name = 'AIRI_IBL_Probe'
+  scene.add(probe)
+
+  function update(mode: EnvMode, intensity: number, sh?: THREE.SphericalHarmonics3 | null) {
+    probe.intensity = (mode === 'skyBox') ? intensity : 0
+    if (sh)
+      probe.sh.copy(sh)
+  }
+  function dispose() {
+    probe.parent?.remove(probe)
+  }
+  return { update, dispose }
+}
diff --git a/packages/stage-ui/src/stores/vrm.ts b/packages/stage-ui/src/stores/vrm.ts
index 4adcd1514..abe3948aa 100644
--- a/packages/stage-ui/src/stores/vrm.ts
+++ b/packages/stage-ui/src/stores/vrm.ts
@@ -82,7 +82,6 @@ export const useVRM = defineStore('vrm', () => {
   // environment related setting
   const envSelect = useLocalStorage('settings/vrm/envEnabled', 'skyBox' as 'hemisphere' | 'skyBox')
   const skyBoxSrc = useLocalStorage('settings/vrm/skyBoxUrl', defaultSkyBoxSrc)
-  const specularMix = useLocalStorage('settings/vrm/specularMix', 0)
   const skyBoxIntensity = useLocalStorage('settings/vrm/skyBoxIntensity', 0.1)
 
   return {
@@ -116,7 +115,6 @@ export const useVRM = defineStore('vrm', () => {
     eyeHeight,
     envSelect,
     skyBoxSrc,
-    specularMix,
     skyBoxIntensity,
 
     shouldUpdateView,