diff --git a/voicevox-remotion-template/src/lib/VQRemotionLib/components/VQCharacterAvatar.tsx b/voicevox-remotion-template/src/lib/VQRemotionLib/components/VQCharacterAvatar.tsx
index d7d752b..24e662f 100644
--- a/voicevox-remotion-template/src/lib/VQRemotionLib/components/VQCharacterAvatar.tsx
+++ b/voicevox-remotion-template/src/lib/VQRemotionLib/components/VQCharacterAvatar.tsx
@@ -184,6 +184,7 @@
         imagePath={imagePath ?? avatar.imagePath}
         mouthImageDir={avatar.mouthImageDir}
         mouth={mouth}
+        mouthCoverLayer={avatar.mouthCoverLayer}
         width={imageWidth}
         height={avatar.imageLayout?.height}
         maxHeight={avatar.imageLayout?.maxHeight ?? 360}
diff --git a/voicevox-remotion-template/src/lib/VQRemotionLib/components/VQLipSyncedStandeeImage.tsx b/voicevox-remotion-template/src/lib/VQRemotionLib/components/VQLipSyncedStandeeImage.tsx
index 32d421b..06f746a 100644
--- a/voicevox-remotion-template/src/lib/VQRemotionLib/components/VQLipSyncedStandeeImage.tsx
+++ b/voicevox-remotion-template/src/lib/VQRemotionLib/components/VQLipSyncedStandeeImage.tsx
@@ -1,11 +1,12 @@
 import React from "react";
 import {Img, staticFile} from "remotion";
-import type {VQMouthShape} from "../types";
+import type {VQMouthCoverLayer, VQMouthShape} from "../types";
 
 export type VQLipSyncedStandeeImageProps = Readonly<{
   imagePath: string;
   mouthImageDir: string;
   mouth: VQMouthShape;
+  mouthCoverLayer?: VQMouthCoverLayer;
   width: number | string;
   maxHeight: number | string;
   height?: number | string;
@@ -13,12 +14,26 @@
   filter?: string;
 }>;
 
+// 用途: 立ち絵の元口を口形画像の直前で隠すかどうか判定する。
+// 使用方法: VQLipSyncedStandeeImage 内で mouthCoverLayer と現在の mouth を渡して使う。
+// オプションや引数詳細: visibleWhen が "activeMouth" の場合は rest で非表示にし、hiddenMouths に含まれる口形でも非表示にする。
+const shouldShowMouthCoverLayer = (
+  mouthCoverLayer: VQMouthCoverLayer | undefined,
+  mouth: VQMouthShape
+) =>
+  Boolean(
+    mouthCoverLayer &&
+      !mouthCoverLayer.hiddenMouths?.includes(mouth) &&
+      (mouthCoverLayer.visibleWhen !== "activeMouth" || mouth !== "rest")
+  );
+
 export const VQLipSyncedStandeeImage: React.FC<
   VQLipSyncedStandeeImageProps
 > = ({
   imagePath,
   mouthImageDir,
   mouth,
+  mouthCoverLayer,
   width,
   maxHeight,
   height,
@@ -47,6 +62,21 @@
           filter,
         }}
       />
+      {shouldShowMouthCoverLayer(mouthCoverLayer, mouth) ? (
+        <div
+          style={{
+            position: "absolute",
+            left: mouthCoverLayer?.left,
+            top: mouthCoverLayer?.top,
+            width: mouthCoverLayer?.width,
+            height: mouthCoverLayer?.height,
+            backgroundColor: mouthCoverLayer?.backgroundColor,
+            borderRadius: mouthCoverLayer?.borderRadius ?? "999px",
+            opacity: mouthCoverLayer?.opacity ?? 1,
+            pointerEvents: "none",
+          }}
+        />
+      ) : null}
       <Img
         src={staticFile(`${mouthImageDir}/${mouth}.png`)}
         style={{
diff --git a/voicevox-remotion-template/src/lib/VQRemotionLib/components/VQStageCornerStandee.tsx b/voicevox-remotion-template/src/lib/VQRemotionLib/components/VQStageCornerStandee.tsx
index 84af501..fb879d8 100644
--- a/voicevox-remotion-template/src/lib/VQRemotionLib/components/VQStageCornerStandee.tsx
+++ b/voicevox-remotion-template/src/lib/VQRemotionLib/components/VQStageCornerStandee.tsx
@@ -1,5 +1,5 @@
 import React from "react";
-import type {VQMouthShape} from "../types";
+import type {VQMouthCoverLayer, VQMouthShape} from "../types";
 import {VQLipSyncedStandeeImage} from "./VQLipSyncedStandeeImage";
 
 export type VQStageCornerStandeeMode = "stage" | "corner";
@@ -53,6 +53,7 @@
   imagePath: string;
   mouthImageDir: string;
   mouth: VQMouthShape;
+  mouthCoverLayer?: VQMouthCoverLayer;
   translateY?: number;
   layouts?: VQStageCornerStandeeLayouts;
   zIndex?: number;
@@ -63,6 +64,7 @@
   imagePath,
   mouthImageDir,
   mouth,
+  mouthCoverLayer,
   translateY = 0,
   layouts = vqDefaultStageCornerStandeeLayouts,
   zIndex = 3,
@@ -89,6 +91,7 @@
         imagePath={imagePath}
         mouthImageDir={mouthImageDir}
         mouth={mouth}
+        mouthCoverLayer={mouthCoverLayer}
         width={layout.imageWidth}
         height={layout.imageHeight}
         maxHeight={layout.imageMaxHeight}
diff --git a/voicevox-remotion-template/src/lib/VQRemotionLib/types.ts b/voicevox-remotion-template/src/lib/VQRemotionLib/types.ts
index 6c420b4..6e9a6f7 100644
--- a/voicevox-remotion-template/src/lib/VQRemotionLib/types.ts
+++ b/voicevox-remotion-template/src/lib/VQRemotionLib/types.ts
@@ -38,10 +38,23 @@
   flipX?: boolean;
 }>;
 
+export type VQMouthCoverLayer = Readonly<{
+  left: number | string;
+  top: number | string;
+  width: number | string;
+  height: number | string;
+  backgroundColor: string;
+  borderRadius?: number | string;
+  opacity?: number;
+  visibleWhen?: "always" | "activeMouth";
+  hiddenMouths?: readonly VQMouthShape[];
+}>;
+
 export type VQAvatarDefinition = Readonly<{
   kind?: string;
   imagePath: string;
   mouthImageDir: string;
+  mouthCoverLayer?: VQMouthCoverLayer;
   imageLayout?: VQAvatarImageLayout;
   accentColor: string;
   nameplatePosition?: VQAvatarNameplatePosition;
diff --git a/voicevox-remotion-template/src/standee-sets.ts b/voicevox-remotion-template/src/standee-sets.ts
index a6e844b..f60d052 100644
--- a/voicevox-remotion-template/src/standee-sets.ts
+++ b/voicevox-remotion-template/src/standee-sets.ts
@@ -1,5 +1,6 @@
 import type {
   VQIdleAvatarAnimationType as IdleAvatarAnimationType,
+  VQMouthCoverLayer,
   VQSpeakingAvatarAnimationType as SpeakingAvatarAnimationType,
 } from "./lib/VQRemotionLib";
 
@@ -21,6 +22,7 @@
   description: string;
   imagePath: string;
   mouthImageDir: string;
+  mouthCoverLayer?: VQMouthCoverLayer;
   imageLayout: StandeeImageLayout;
 }>;
 
@@ -98,6 +100,16 @@
     description: "小夜の立ち絵（SAYONAKA 素材）",
     imagePath: "image/sayo_by_sayonaka/variants/sayo_001_neutral.png",
     mouthImageDir: "image/sayo_by_sayonaka/rhubarb-mouths",
+    mouthCoverLayer: {
+      left: "48.4%",
+      top: "33.65%",
+      width: "4.35%",
+      height: "2.25%",
+      backgroundColor: "#fff8ef",
+      borderRadius: "50%",
+      visibleWhen: "activeMouth",
+      hiddenMouths: ["rest", "closed"],
+    },
     imageLayout: {
       width: 520,
       maxHeight: 720,