diff --git a/src/infrastructures/supertokens/appInfo.ts b/src/infrastructures/supertokens/appInfo.ts
index 1b67fbdc..5e9a97cf 100644
--- a/src/infrastructures/supertokens/appInfo.ts
+++ b/src/infrastructures/supertokens/appInfo.ts
@@ -1,6 +1,6 @@
 export const appInfo = {
   // cf. https://supertokens.com/docs/emailpassword/nextjs/app-directory/init
-  appName: 'TraceDojo',
+  appName: 'トレース道場',
   apiDomain: process.env.NEXT_PUBLIC_BASE_URL ?? '',
   websiteDomain: process.env.NEXT_PUBLIC_BASE_URL ?? '',
   apiBasePath: '/api/auth',
diff --git a/src/infrastructures/supertokens/frontendConfig.ts b/src/infrastructures/supertokens/frontendConfig.ts
index 42bf3ae7..d30a3153 100644
--- a/src/infrastructures/supertokens/frontendConfig.ts
+++ b/src/infrastructures/supertokens/frontendConfig.ts
@@ -129,6 +129,7 @@ export const frontendConfig = (): SuperTokensConfig => {
           ERROR_NON_OPTIONAL: 'このフィールドは必須です',
         },
       },
+      defaultLanguage: 'ja',
     },
   };
 };