diff --git a/locales/en-US/common.json b/locales/en/common.json
similarity index 100%
rename from locales/en-US/common.json
rename to locales/en/common.json
diff --git a/locales/en-US/index.json b/locales/en/index.json
similarity index 100%
rename from locales/en-US/index.json
rename to locales/en/index.json
diff --git a/locales/en-US/profile.json b/locales/en/profile.json
similarity index 95%
rename from locales/en-US/profile.json
rename to locales/en/profile.json
index e113de5..4a7e260 100644
--- a/locales/en-US/profile.json
+++ b/locales/en/profile.json
@@ -14,7 +14,7 @@
     "contact": "Get in touch",
     "belongs": "Organization",
     "more": "More...",
-    "grade": "(1st grade)",
+    "grade": "B2",
     "icon_1": "Icon: ",
     "icon_2": ""
 }
\ No newline at end of file
diff --git a/locales/en-US/status.json b/locales/en/status.json
similarity index 100%
rename from locales/en-US/status.json
rename to locales/en/status.json
diff --git a/locales/ja-JP/common.json b/locales/ja/common.json
similarity index 100%
rename from locales/ja-JP/common.json
rename to locales/ja/common.json
diff --git a/locales/ja-JP/index.json b/locales/ja/index.json
similarity index 100%
rename from locales/ja-JP/index.json
rename to locales/ja/index.json
diff --git a/locales/ja-JP/profile.json b/locales/ja/profile.json
similarity index 96%
rename from locales/ja-JP/profile.json
rename to locales/ja/profile.json
index b38de94..158d302 100644
--- a/locales/ja-JP/profile.json
+++ b/locales/ja/profile.json
@@ -14,7 +14,7 @@
     "contact": "連絡先 / SNS",
     "belongs": "所属",
     "more": "さらに見る...",
-    "grade": "1年",
+    "grade": "2年",
     "icon_1": "アイコン: ",
     "icon_2": "さん"
 }
\ No newline at end of file
diff --git a/locales/ja-JP/status.json b/locales/ja/status.json
similarity index 100%
rename from locales/ja-JP/status.json
rename to locales/ja/status.json
diff --git a/next.config.js b/next.config.js
index 9950dba..a672f1c 100644
--- a/next.config.js
+++ b/next.config.js
@@ -7,9 +7,9 @@ module.exports = nextTranslate({
     i18n: {
       // These are all the locales you want to support in
       // your application
-      locales: ['ja-JP', 'en-US'],
+      locales: ['ja', 'en'],
       // This is the default locale you want to be used when visiting
       // a non-locale prefixed path e.g. `/hello`
-      defaultLocale: 'ja-JP',
+      defaultLocale: 'ja',
     }
   })
\ No newline at end of file
diff --git a/pages/components/LangSelector.js b/pages/components/LangSelector.js
index 75edcaa..9b53452 100644
--- a/pages/components/LangSelector.js
+++ b/pages/components/LangSelector.js
@@ -48,10 +48,10 @@ const Dropdown = ({ color }) => {
   <div ref={popoverDropdownRef} className={
               (dropdownPopoverShow ? "block " : "hidden ") + "origin-top-right absolute right-0 mt-2 w-40 rounded-md shadow-lg bg-white ring-1 ring-black ring-opacity-5"}>
     <div className="py-1" role="menu" aria-orientation="vertical" aria-labelledby="options-menu">
-    <Link href="#" locale="ja-JP">
+    <Link href="#" locale="ja">
       <a href="#" className="block px-4 py-2 text-sm text-gray-700 hover:bg-gray-100 hover:text-gray-900" role="menuitem">日本語</a>
     </Link>
-    <Link href="#" locale="en-US">
+    <Link href="#" locale="en">
       <a href="#" className="block px-4 py-2 text-sm text-gray-700 hover:bg-gray-100 hover:text-gray-900" role="menuitem">English</a>
     </Link>
     </div>