diff --git a/locales/ja-JP.yml b/locales/ja-JP.yml
index 4aaf63b628..6286367b50 100644
--- a/locales/ja-JP.yml
+++ b/locales/ja-JP.yml
@@ -1148,7 +1148,7 @@ _achievements:
       description: "ここをクリックした"
     _justPlainLucky:
       title: "単なるラッキー"
-      description: "10秒ごとに0.01%の確率で獲得"
+      description: "10秒ごとに0.005%の確率で獲得"
     _setNameToSyuilo:
       title: "神様コンプレックス"
       description: "名前を syuilo に設定した"
diff --git a/packages/frontend/src/init.ts b/packages/frontend/src/init.ts
index 4227f5cf4a..64c252ce55 100644
--- a/packages/frontend/src/init.ts
+++ b/packages/frontend/src/init.ts
@@ -438,7 +438,7 @@ if ($i) {
 	}
 
 	window.setInterval(() => {
-		if (Math.floor(Math.random() * 10000) === 0) {
+		if (Math.floor(Math.random() * 20000) === 0) {
 			claimAchievement('justPlainLucky');
 		}
 	}, 1000 * 10);