diff --git a/quartz.config.ts b/quartz.config.ts
index 9392eb66..6751a6c1 100644
--- a/quartz.config.ts
+++ b/quartz.config.ts
@@ -6,7 +6,7 @@ const config: QuartzConfig = {
     pageTitle: "Matsuura Tomoya Research Note",
     enableSPA: true,
     enablePopovers: true,
-    locale: "en-US",
+    locale: "ja-JP",
     analytics: {
       provider: "plausible",
     },