diff --git a/common.nix b/common.nix
index aa1b3c87..c7a6825f 100644
--- a/common.nix
+++ b/common.nix
@@ -6,9 +6,9 @@
   ];
 
   # locale
-  i18n.defaultLocale = "en_US.UTF-8";
+  i18n.defaultLocale = "ja_JP.UTF-8";
   i18n.supportedLocales =
-    [ "en_US.UTF-8/UTF-8" "ja_JP.UTF-8/UTF-8" "fr_FR.UTF-8/UTF-8" ];
+    [ "ja_JP.UTF-8/UTF-8" "en_US.UTF-8/UTF-8" "fr_FR.UTF-8/UTF-8" ];
 
   # nix
   nix = {