diff --git a/README.md b/README.md
index ffa2393..3367915 100644
--- a/README.md
+++ b/README.md
@@ -94,7 +94,7 @@ RobotVRMはオープンソースの、**pixiv**の[**pixiv/ChatVRM**](https://gi
 </p>
 
 <h3 align="center">
- <img src="./docs/sponsor_icon/dragon.jpg" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">ドラゴンスポンサー US$1万2千(最大)</a>
+ <img src="./docs/sponsor_icon/dragon.webp" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">ドラゴンスポンサー US$1万2千(最大)</a>
 </h3>
 
 <p align="center">
@@ -102,7 +102,7 @@ RobotVRMはオープンソースの、**pixiv**の[**pixiv/ChatVRM**](https://gi
 </p>
 
 <h3 align="center">
-<img src="./docs/sponsor_icon/hero.jpg" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">勇者スポンサー US$1万</a>
+<img src="./docs/sponsor_icon/hero.webp" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">勇者スポンサー US$1万</a>
 </h3>
 
 <p align="center">
@@ -110,7 +110,7 @@ RobotVRMはオープンソースの、**pixiv**の[**pixiv/ChatVRM**](https://gi
 </p>
 
 <h3 align="center">
-<img src="./docs/sponsor_icon/devilking.jpg" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">魔王スポンサー US$5,000</a>
+<img src="./docs/sponsor_icon/devilking.webp" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">魔王スポンサー US$5,000</a>
 </h3>
 
 <p align="center">
@@ -118,7 +118,7 @@ RobotVRMはオープンソースの、**pixiv**の[**pixiv/ChatVRM**](https://gi
 </p>
 
 <h3 align="center">
-<img src="./docs/sponsor_icon/elf.jpg" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">エルフスポンサー US$1,000</a>
+<img src="./docs/sponsor_icon/elf.webp" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">エルフスポンサー US$1,000</a>
 </h3>
 
 <p align="center">
@@ -126,7 +126,7 @@ RobotVRMはオープンソースの、**pixiv**の[**pixiv/ChatVRM**](https://gi
 </p>
 
 <h3 align="center">
-<img src="./docs/sponsor_icon/demon.jpg" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">デーモンスポンサー US$500</a>
+<img src="./docs/sponsor_icon/demon.webp" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">デーモンスポンサー US$500</a>
 </h3>
 
 <p align="center">
@@ -134,7 +134,7 @@ RobotVRMはオープンソースの、**pixiv**の[**pixiv/ChatVRM**](https://gi
 </p>
 
 <h3 align="center">
-<img src="./docs/sponsor_icon/wizard.jpg" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">魔法使いスポンサー US$100</a>
+<img src="./docs/sponsor_icon/wizard.webp" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">魔法使いスポンサー US$100</a>
 </h3>
 
 <p align="center">
@@ -142,7 +142,7 @@ RobotVRMはオープンソースの、**pixiv**の[**pixiv/ChatVRM**](https://gi
 </p>
 
 <h3 align="center">
-<img src="./docs/sponsor_icon/auger.jpg" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">オーガスポンサー US$50</a>
+<img src="./docs/sponsor_icon/auger.webp" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">オーガスポンサー US$50</a>
 </h3>
 
 <p align="center">
@@ -150,7 +150,7 @@ RobotVRMはオープンソースの、**pixiv**の[**pixiv/ChatVRM**](https://gi
 </p>
 
 <h3 align="center">
-<img src="./docs/sponsor_icon/warrior.jpg" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">戦士スポンサー US$10</a>
+<img src="./docs/sponsor_icon/warrior.webp" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">戦士スポンサー US$10</a>
 </h3>
 
 <p align="center">
@@ -158,7 +158,7 @@ RobotVRMはオープンソースの、**pixiv**の[**pixiv/ChatVRM**](https://gi
 </p>
 
 <h3 align="center">
-<img src="./docs/sponsor_icon/wolf.jpg" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">ウルフスポンサー US$5</a>
+<img src="./docs/sponsor_icon/wolf.webp" height="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">ウルフスポンサー US$5</a>
 </h3>
 
 <p align="center">
@@ -166,7 +166,7 @@ RobotVRMはオープンソースの、**pixiv**の[**pixiv/ChatVRM**](https://gi
 </p>
 
 <h3 align="center">
-<img src="./docs/sponsor_icon/slime.jpg" width="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">スライムスポンサー US$1</a>
+<img src="./docs/sponsor_icon/slime.webp" width="51" style="vertical-align: middle"> <a href="https://github.com/sponsors/saten-private">スライムスポンサー US$1</a>
 </h3>
 
 <p align="center">
diff --git a/docs/sponsor_icon/auger.jpg b/docs/sponsor_icon/auger.jpg
deleted file mode 100644
index dd4297b..0000000
Binary files a/docs/sponsor_icon/auger.jpg and /dev/null differ
diff --git a/docs/sponsor_icon/demon.jpg b/docs/sponsor_icon/demon.jpg
deleted file mode 100644
index c53582f..0000000
Binary files a/docs/sponsor_icon/demon.jpg and /dev/null differ
diff --git a/docs/sponsor_icon/devilking.jpg b/docs/sponsor_icon/devilking.jpg
deleted file mode 100644
index ba6107d..0000000
Binary files a/docs/sponsor_icon/devilking.jpg and /dev/null differ
diff --git a/docs/sponsor_icon/dragon.jpg b/docs/sponsor_icon/dragon.jpg
deleted file mode 100644
index cd738d0..0000000
Binary files a/docs/sponsor_icon/dragon.jpg and /dev/null differ
diff --git a/docs/sponsor_icon/elf.jpg b/docs/sponsor_icon/elf.jpg
deleted file mode 100644
index 038246c..0000000
Binary files a/docs/sponsor_icon/elf.jpg and /dev/null differ
diff --git a/docs/sponsor_icon/hero.jpg b/docs/sponsor_icon/hero.jpg
deleted file mode 100644
index 46d4d7e..0000000
Binary files a/docs/sponsor_icon/hero.jpg and /dev/null differ
diff --git a/docs/sponsor_icon/slime.jpg b/docs/sponsor_icon/slime.jpg
deleted file mode 100644
index b45d103..0000000
Binary files a/docs/sponsor_icon/slime.jpg and /dev/null differ
diff --git a/docs/sponsor_icon/warrior.jpg b/docs/sponsor_icon/warrior.jpg
deleted file mode 100644
index bcbabc4..0000000
Binary files a/docs/sponsor_icon/warrior.jpg and /dev/null differ
diff --git a/docs/sponsor_icon/wizard.jpg b/docs/sponsor_icon/wizard.jpg
deleted file mode 100644
index ee66bbd..0000000
Binary files a/docs/sponsor_icon/wizard.jpg and /dev/null differ
diff --git a/docs/sponsor_icon/wolf.jpg b/docs/sponsor_icon/wolf.jpg
deleted file mode 100644
index 1ffcc33..0000000
Binary files a/docs/sponsor_icon/wolf.jpg and /dev/null differ