Up your language skills. By watching your favorite shows.

Double interactive subtitles for Japanese on Netflix, plus a web companion for reading practice on topics you choose. Word cards, explanations, and Anki sync — backed by technology tailored for Japanese learners.

Get the Extension Why it works

Japanese + any Netflix secondary subtitle · free forever · 7-day free trial for Pro

Tap any word for the word card
僕らぼくらはみんな関係ないかんけいないふりをしていた

We were all pretending it had nothing to do with us.

14:32
23:41
known fragile new — colored by your Anki vocabulary

The science behind it

Comprehensible input is the engine of fluency — the triple reinforcement loop keeps it turning.

Decades of research (Krashen, Nation, Webb) agree: acquisition happens when you understand meaningful input slightly above your level — not through drills alone, but through real language in context.

1

Hear it in context

Native audio in a memorable scene builds the first memory trace.

2

Save & practice in Anki

One-click cards and spaced repetition move words into long-term memory.

3

See it highlighted next time

Familiarity colors in subtitles trigger recall and speed acquisition.

The cycle repeats every episode — comprehensible input in action.

20×

More effective — incidental vocabulary from comprehensible input vs. word lists (Webb & Nation, 2017)

8–12

Encounters — typical range to move a word toward production. Subtitles give natural repeats (Nation, 2001)

95%

Coverage threshold — for comfortable reading. Familiarity highlighting shows where you are (Laufer, 1989)

Purpose-built NLP

We actually understand Japanese

Instead of using generic, multi-language text processing for Japanese — a language with no spaces, complex conjugation, and thousands of compound expressions — we built our entire NLP pipeline specifically for Japanese.

Wrong word boundaries

Every other extension uses generic multi-language tokenizers that break Japanese into random fragments. They can't tell where one word ends and another begins — because Japanese has no spaces.

Our Sudachi-powered morphological analyzer understands Japanese grammar natively. It recognizes 食べたくなかった as a single conjugated verb phrase and decomposes it into its meaningful components — stem, auxiliary verbs, negation, tense.

Others

食べ / たくな / かった

uplang

食べたくなかった → 食べる (eat) + たい (want) + ない (not) + past

Missed compound expressions

Generic tools split 気持ち into 気 + 持ち and tell you it means "spirit" + "hold." That's technically correct and completely useless. Real Japanese is full of compounds, idioms, and set phrases.

Our custom token merging algorithm detects compound expressions, verb phrases, and idiomatic constructions by cross-referencing against 328,000 JMdict entries. You get the meaning that actually matters.

Others

気 → "spirit" + 持ち → "hold"

uplang

気持ち → feeling, sensation Compound recognized as single lexeme

Context beyond the dictionary

Correct boundaries and dictionary senses get you partway there — but they don't explain tone, register, or why a phrase means what it means in this line. A gloss is not the same as understanding.

Select any word or phrase and get an LLM explanation grounded in the full line and scene. Grammar, implication, and how people actually use the language — not a one-line textbook definition.

Others

やばい → ① dangerous ② terrible ③ awful

uplang

Here it's hype: "that's wild!" — not literal danger. AI explains nuance in this subtitle

Full immersion toolkit — learn from what you watch

Japanese plus a second subtitle in any language Netflix lists for that title stays free forever. Pro unlocks the Chrome extension and the web reader on one account: the same Sudachi + JMdict pipeline for interactive lookups on Netflix, and AI-generated reading practice in your browser when you are not watching.

Dual Subtitles

Free

Japanese plus a second subtitle in any language Netflix offers for that title — pick the track in the extension. Both lines stay perfectly synced so you see the original and a translation side by side as you watch.

Pro includes

Interactive Word Cards

Hover any word for instant readings, conjugation breakdowns, and up to 5 dictionary definitions — all from 328,000 JMdict entries. No loading, no network delay.

Phrase Selection Breakdown

Drag to select any phrase in the subtitles. Get a token-by-token breakdown with readings, POS, and glosses — then ask the AI to explain the whole span in context.

AI Explanations

Don't just see definitions — understand nuance. Our AI explains grammar patterns, contextual meaning, and usage in the exact sentence you're watching.

Furigana & playback controls

Furigana: always, unknown-only, hover, or off — plus Japanese subtitle and word-card sizing. Secondary-line timing, pause-on-hover, arrow key controls, and more.

One-Click Anki Cards

Create flashcards with full sentence context, translation, reading, and part of speech. Your Anki vocabulary syncs back to power familiarity highlighting.

Familiarity Highlighting

Every word is color-coded by your actual Anki deck data. Known words fade to the background. Fragile words catch your eye. New words stand out instantly.

Separate web app · same Pro login

Web companion — reading practice

When you are not on Netflix, open the companion in your browser with the same account. It is built for longer-form study: generate passages on demand, re-read them with the same interactive tooling as the extension, and track how well each text fits your vocabulary.

  • AI-generated Japanese text from any topic you type (plus suggested topics and one-tap random ideas)
  • Length and formality controls so passages match your study window and register
  • Full Sudachi + JMdict pipeline — identical tokenization, glosses, and morpheme breakdowns as on Netflix
  • Interactive reading view: hover tokens, explore compounds, and use the same dictionary depth you get in the extension
  • Comprehension scoring and per-session stats so you see how challenging each text was
  • Session history: reopen past generations and build a library of readings over time

From install to immersion in 60 seconds

1

Install & press play

Add the extension to Chrome and sign in. Start a Netflix show with Japanese subtitles and choose the secondary language in the extension — any subtitle track Netflix lists for that title, not only English. The overlay activates automatically.

2

Everything loads instantly

The full episode is tokenized, merged, and annotated blazingly fast — not minutes. By the first subtitle, every word card, reading, and dictionary entry is ready.

3

Watch, look up, save, repeat

Hover words for instant definitions. Ask the AI about grammar. One-click save to Anki. Next time you see that word highlighted, your brain already knows it.

Purpose-built beats one-size-fits-all

We do one language, and we do it right.

Japanese morphological analysis (Sudachi NLP)

Gold-standard vs Generic multi-language or none

Token merging & compound detection (気持ち, 食べたい, 関係ない)

Custom algorithm vs Missed — split into fragments

Full episode tokenization speed

~50ms total vs Seconds, or line-by-line delay

Contextual AI explanations (grammar + nuance)

Yes vs Generic machine translation

Working Anki integration + vocabulary sync

Yes vs Broken or absent

Familiarity highlighting from your actual Anki data

Yes vs Generic frequency lists

Built exclusively for Japanese

100% focused vs 10–27 languages, none done well

Simple, transparent pricing

Dual subtitles (Japanese + any secondary language Netflix offers) are free forever. Upgrade to Pro for the most efficient learning experience possible.

Monthly

$6.99 /mo
Start 7-day free trial
Save 17%

Annual

$69 /yr
~$5.75/mo Start 7-day free trial

Everything in Pro:

  • Interactive word cards
  • Furigana, sizing & playback controls
  • AI-powered grammar explanations
  • Anki integration (one-click cards)
  • Familiarity highlighting
  • Text selection breakdown
  • Web app companion for reading practice

Dual subtitles (Japanese + your choice of secondary track) are free forever. No account needed.

Frequently asked questions

What do I get for free?
Dual subtitles (Japanese plus any secondary subtitle Netflix lists for that title — English, Spanish, Korean, etc.) are completely free, forever. You choose the language in the extension. This alone lets you follow along with native content. All other features — interactive word cards, phrase selection breakdown, AI explanations, furigana and playback controls, Anki integration, familiarity highlighting, and the web reading companion — are part of the paid plan.
Which streaming platforms are supported?
Netflix is fully supported today. YouTube support is on the roadmap.
Do I need to know Japanese to use this?
The extension is designed for learners who can read hiragana and katakana. It's most useful from upper-beginner level onward (JLPT N4+), where comprehensible input becomes the most effective way to acquire vocabulary and grammar.
How is this different from Language Reactor or Migaku?
Those tools support many languages with generic text processing. We use Sudachi — Japan's gold-standard morphological analyzer — for correct word boundaries and compound handling. Our custom token merging algorithm identifies multi-word expressions like 食べたくなかった and 関係ない as single units. We also tokenize the entire episode in milliseconds (not seconds), and our AI explains grammar in context rather than giving generic translations.
How does the Anki integration work?
One click creates a flashcard with the word, reading, part of speech, glosses, and the full sentence context (Japanese plus your secondary subtitle line). Your Anki vocabulary then syncs back to the extension to power familiarity highlighting — creating a feedback loop where words you're studying in Anki are automatically highlighted when they appear in subtitles.
What is the web companion?
Pro includes access to our web app with the same account. You can generate Japanese reading passages on any topic, with controls for length and formality. Text is tokenized with the same Sudachi + JMdict pipeline as Netflix, with interactive lookups, comprehension scoring, and session history — ideal for study when you are not watching a show.
What display and playback options does the Netflix extension offer?
Pro settings cover both reading aids and the player experience. Furigana can be always on, limited to words you do not know yet, shown on hover, or off. You can scale Japanese subtitle text and word-card popovers, and shift the overlay vertically. The secondary subtitle line can follow the video always, only when you pause, only when you hover the subtitle area, or stay hidden. Optional pause-on-hover keeps the video still while you read; left and right arrow keys jump to the previous or next subtitle line instead of using Netflix's default 10-second skip.
Is it really that fast?
Yes. Our NLP pipeline tokenizes, merges compounds, and annotates every subtitle in a full episode in roughly 50 milliseconds. By the time the first subtitle appears on screen, every word card in the entire episode is ready. There is zero per-line delay.
Is comprehensible input really more effective than textbooks?
Research overwhelmingly supports it. Stephen Krashen's input hypothesis, Nation's work on incidental vocabulary acquisition, and Webb's studies on learning from TV all show that understanding meaningful, contextual input at your level is far more effective than decontextualized study. Our extension turns Netflix into that comprehensible input — with dictionary support, translations, and highlighting calibrated to your exact vocabulary level.
How much does it cost?
Dual subtitles are free forever — no account needed. Pro features (word cards, phrase breakdown, furigana and playback controls, AI explanations, Anki integration, highlighting, web reading) are $6.99/month or $69/year (~$5.75/mo). Every paid plan starts with a 7-day free trial.
Can I cancel anytime?
Yes. Cancel in one click from your profile page. You keep Pro access until the end of your current billing period — no questions asked.
Is my data private?
Only subtitle text is sent to our servers for analysis. No video data, no browsing history, no personal information beyond your account email. Payments are processed securely by Stripe — we never see your card details.

Every episode is a lesson waiting to happen

Dual subtitles are free. Upgrade to Pro for interactive word cards, phrase breakdowns, AI explanations, furigana and playback controls, Anki integration, web reading practice, and more.

Get the Extension View pricing

Dual subtitles free forever. 7-day free trial for Pro — no credit card required to start.