Beta · Language Reactor for the open web

Watch & learn

Watch any YouTube video with side-by-side captions, click words for definitions, save them to a deck, and study at your level. Curated learner channels in 4 languages.

🃏 My saved words →

All57 🇬🇧English16 🇯🇵日本語16 🇪🇸Español14 🇫🇷Français11

🇯🇵日本語

Starter videos

"Duolingo Says ませんか is 'Would You Like To'?"

That Japanese Man Yuta10 min

Native explanation of polite-form invitation patterns.

Still Saying あなた? Try This

That Japanese Man Yuta19 min

When (not) to use あなた in real Japanese.

Seika's Favorite Book — Complete Beginner Japanese

Comprehensible Japanese6 min

Slow visual Japanese for absolute beginners.

Japanese Nursery Rhyme: Open Shut Them

Comprehensible Japanese10 min

Comprehensible-input lesson via a nursery rhyme.

Learn 80+ Japanese Words — Dragon Ball Z: Kakarot

Game Gengo24 min

Vocabulary and grammar through a famous JRPG.

Beginner Japanese with Ni No Kuni — N5/N4 Vocabulary

Game Gengo30 min

JLPT N5/N4 vocab through video games.

How to Know If Someone Likes You

Onomappu11 min

Vlog-style conversational Japanese with bilingual subs.

ている/ています (To be -ing) TE Form Lesson Pt.2

Japanese Ammo with Misa19 min

Detailed grammar explanation of the te-form.

JLPT N3 Reading Practice — "Hanasaka Jiisan"

Japanese Ammo with Misa28 min

JLPT N3 reading comprehension through a folktale.

Channels worth following

Comprehensible Japanese

beginner

Slow, visual Japanese designed for input-based learning. Real subtitles, no English.

@cijapanese

Let's ask Shogo (Japan)

intermediate

Japanese culture and language explained from a native perspective — clear captions.

@LetsaskShogo

NHK ニュース

all

NHK's official YouTube — newsclips with captions; mix of natural and easy Japanese.

@nhk

That Japanese Man Yuta

intermediate

Street interviews and culture explainers — bilingual captions, conversational Japanese.

@ThatJapaneseManYuta

Game Gengo

intermediate

Learn Japanese vocabulary and grammar via popular video games. Hugely popular in language-learning communities.

@GameGengo

Onomappu

intermediate

Japanese culture and language vlogs at conversational pace — clear bilingual subtitles.

@Onomappu

Japanese Ammo with Misa

all

Detailed grammar explanations from N5 to N2 — long-form lessons with thorough captions.

@JapaneseAmmowithMisa

Phase 1 · what works today

YouTube IFrame player + side-by-side caption strip pulled from YT's public timedtext feed
Curated starter videos + recommended channels in 4 languages
Paste any YouTube URL or video ID to watch + read captions

Phase 2 · coming next

Click-to-define popovers (JMdict for 🇯🇵, Wiktionary for 🇪🇸/🇫🇷)
Furigana ふりがな over kanji via kuromoji.js
YouGlish-style word search across captioned videos