A free, interactive course that teaches Japanese the way a good programming tutorial teaches a language: every concept motivated before the mechanics, every example a real situation.
47 chapters · beginner to advanced · English & 简体中文 · every sentence type-checked
Most textbooks hand you a rule and a table. This course works like documentation for a language you already think in.
Motivated, not memorized
Every grammar point starts from a sentence you can't say yet, then introduces the form that fixes it — the way a tutorial introduces a new concept only once you feel the need for it.
Every example type-checks
Each sentence is a self-contained TypeScript snippet whose types prove it is grammatically well-formed. Open any example in the interactive analyzer to take it apart, particle by particle.
Bilingual & beginner-first
Written in natural English and 简体中文 at equal depth, assuming zero prior Japanese. Concepts arrive in dependency order, so nothing ever depends on something you have not met.
A sentence is a type
This is what every example in the course looks like under the hood — and what the built-in analyzer lets you explore live.
// A chapter example, as a typed sentence you can pull aparttype ヒンメル = ProperNoun<"ヒンメル">;
// The irregular verb "する" (to do)type する = IrregularVerb & { dictionary: "する" };
// "そうした" — did sotype そうした = DemonstrativeAction<Demonstrative & "そう", する, "た形">;
// "If it were Himmel, he would have done so"type ヒンメルならそうした = ConditionalPhrase<ヒンメル, "なら", そうした>;
// The type system proves the sentence is well-formed:const ok: ヒンメルならそうした = "ヒンメルならそうした"; // ✓ type-checksA path from zero to fluent reading
Three levels, each building on the last — from your first “A は B です” to keigo and literary style.
Elementary
初级 · 20 章
Noun sentences, particles, verbs and the て-form, adjectives, past tense, comparison, conditionals, desire and obligation — the bedrock for saying what you do and want.
Intermediate
中级 · 15 章
Passive and causative, the full keigo system, conditionals revisited, giving and receiving, appearance and hearsay, transitivity, and the connectives that link real sentences.
Advanced
高级 · 12 章
Business keigo, nuanced suffixes, the わけ family, formal and literary patterns, and the written style you meet in essays, news, and novels.
Ready when you are
The whole course runs in your browser — free, open source, no signup. Start at chapter one, or jump to whatever grammar is giving you trouble.
Start learning Japanese →Also exploring the same idea for English — Typed English.