diff --git a/l10n/ja/viewer.properties b/l10n/ja/viewer.properties
index c8bfde461..eb584d5e7 100644
--- a/l10n/ja/viewer.properties
+++ b/l10n/ja/viewer.properties
@@ -50,6 +50,10 @@ thumb_page_title={{page}} ページ
 # number.
 thumb_page_canvas=ページの縮小版 {{page}}
 
+# Context menu
+page_rotate_cw=Rotate Clockwise
+page_rotate_ccw=Rotate Counter-Clockwise
+
 # Search panel button title and messages
 search=検索
 search_terms_not_found=(見つかりませんでした)