Niconico Japanese Enforcer от Iheon

Niconico Japanese Enforcer keeps Niconico in Japanese even when the site would otherwise switch to English or another language.

It forces the Japanese locale for Niconico page requests, API requests, browser language detection, and comment requests. This includes the main site interface, video pages, player-related requests, and comments.

The extension does not translate user-generated content. Video titles, descriptions, and comments remain exactly as posted by their authors.

No browsing history, account information, personal data, analytics, or telemetry is collected or transmitted.