SubSensei

About

SubSensei turns Crunchyroll into a Japanese study tool. It overlays accurate, perfectly-synced Japanese subtitles on the anime you're already watching — and makes every line interactive, so you can learn straight from native dialogue instead of textbook sentences.

WHAT IT DOES

• Synced Japanese subtitles — SubSensei sources Japanese subtitles from the Jimaku community subtitle database and automatically aligns them to the exact timing of the episode you're watching, so the words match what's being said on screen.

• Instant hover dictionary — point at any Japanese word to see its reading and definition right away, with common-word and JLPT level tags to help you focus on what's worth learning.

• Dual subtitles — show Japanese and English at the same time when you want the meaning of a full line at a glance.

• Fully adjustable overlay — drag to reposition, resize the text, change colors, and set the background opacity so the subtitles sit exactly where you want them.

• Fast and offline-friendly — aligned subtitles are cached locally in your browser, so repeat views load instantly.

WHY INSTALL IT

If you're learning Japanese, watching real anime is one of the most enjoyable ways to build listening comprehension and vocabulary — but only if you can actually read along and look up what you don't know. SubSensei removes that friction: accurate Japanese subtitles appear in sync, and any unfamiliar word is one hover away from a definition. No pausing to type into a dictionary, no switching tabs, no guessing.

It's built for learners at every level — from beginners leaning on dual subtitling Japanese-only and checking the occasional word.

GETTING STARTED

SubSensei sources its Japanese subtitles from Jimaku, which requires a free APInute:

1. Go to jimaku.cc and create a free account (or sign in).
2. Open your account page at jimaku.cc/account.
3. Copy your API key from that page.
4. Click the SubSensei icon (or open its Options page) and paste the key into the "Jimaku API key" field.

Your key is stored locally in your browser and is only ever sent to Jimaku to download subtitles. Once it's saved, open any Crunchyroll episode and the synced Japanese subtitles appear
automatically.

PRIVATE BY DESIGN

SubSensei has no backend of its own and runs no analytics or tracking. Your setand your API key are stored locally in your browser and never uploaded to us.Network requests go only to the services needed to fetch the subtitles and definitions you ask for (Jimaku, AniList, Jisho, and Crunchyroll). See the privacy policy for full details.

Made for Japanese learners who'd rather study with the shows they love.