About Kotojutsu
Kotojutsu is a free website for learning Japanese, from your first hiragana to JLPT N1. Here is who makes it, how its content is written and checked, where its data comes from, and what to do if you spot a mistake.
Who makes Kotojutsu
Kotojutsu is a personal, non-commercial project, created and run by Clément, a computer engineering student. The code, teaching texts, exercises and design are his, except the open works listed below.
The site sells nothing and shows no advertising. The course, reviews, flashcards, practice tests and Densha, the AI assistant, are free. Those who wish can support the project with a donation, which is optional and gives nothing in return: it unlocks nothing.
For any question: [email protected], or Kotojutsu's Discord server. The details are in the legal notice.
The aim, and the method
A complete, free course in plain language, from kana to N1, following the JLPT syllabus level by level: 2,383 kanji, 8,010 words and 528 grammar points. The site also aims to be a reference: a grammar lesson, a kanji page or a dictionary entry has to be right.
Kanji are learnt in real words, and the exercises have you read in context: reciting “on'yomi, kun'yomi” won't help you read 今日.
Every grammar point has its lesson, examples read by a Japanese voice, exercises and fill-in-the-blank sentences.
Reviews use spaced repetition (the FSRS algorithm): each kana, kanji, word or grammar point comes back just before you forget it.
How the content is written and reviewed
Written for the course
The grammar lessons, exercises, readings, fill-in-the-blank sentences and practice tests are original content, written for Kotojutsu in the order of the course: a kanji is taught before the words that use it.
Based on reference sources
Readings, meanings and stroke shapes come from well-known open dictionaries (JMdict, KANJIDIC2, KanjiVG). The JLPT level of words and kanji comes from Jonathan Waller's lists: there is no official list.
Checked at every update
Automated tests check all the content before each release: readings and grammar only use the kanji of their level, every practice test follows the format of its level, each kanji's stroke count matches its strokes, every grammar point has a complete lesson.
Reviewed in full
In October 2026, the 50 practice tests were reviewed question by question. In November 2026, two complete reviews followed, one after the other: the lessons from N5 to N1, the exercises, the fill-in-the-blank sentences, the practice tests and the flashcards, one by one. The corrections are listed in what's new.
Fixed thanks to your reports
Every report is read, and the mistake is fixed in the content itself, for everyone.
The English version is translated from French, which remains the reference, and is being reviewed bit by bit. The English meanings of words and kanji come from JMdict and KANJIDIC2.
Densha, the AI assistant of the lessons and grammar, is a language model: it can make mistakes. The lessons themselves are not generated on the fly.
Where the data comes from
Kotojutsu builds on these open works. Thanks to their authors.
KanjiVG
Stroke shapes and stroke order of the kanji and kana. The strokes redistributed by Kotojutsu remain under the same licence.
© Ulrich Apel and contributors. Creative Commons Attribution-ShareAlike 3.0 (CC BY-SA 3.0).
JMdict
Flashcard dictionary: written forms, readings, French and English meanings, word frequency. Kotojutsu's dictionary, derived from it, remains under the same licence.
© Electronic Dictionary Research and Development Group. Creative Commons Attribution-ShareAlike 4.0 (CC BY-SA 4.0).
KANJIDIC2
JLPT N4 to N1 kanji decks: meanings, readings, stroke count and frequency of each kanji.
© Electronic Dictionary Research and Development Group. Creative Commons Attribution-ShareAlike 4.0 (CC BY-SA 4.0).
Jonathan Waller's JLPT lists
Split of kanji and words by JLPT level (N5 to N1). There is no official list: these lists, also used by Jisho, are the reference.
© Jonathan Waller; matched to JMdict by Stephen Kraus (yomitan-jlpt-vocab). Creative Commons Attribution (CC BY).
French Wiktionary
French meanings of the Japanese words in the flashcard dictionary.
© the French Wiktionary contributors, extracted by kaikki.org (wiktextract, Tatu Ylonen). Creative Commons Attribution-ShareAlike 4.0 (CC BY-SA 4.0).
Dela Gothic One, Zen Kaku Gothic New, Klee One
Typefaces, served directly by the site.
© artakana (Dela Gothic One), Yoshimichi Ohira (Zen Kaku Gothic New), Fontworks (Klee One). SIL Open Font License 1.1.
gpt-oss-120b
Language model behind Densha, the AI assistant of the lessons and grammar.
OpenAI, run by Groq. Apache License 2.0.
SpeechGen
Audio of the single kana (あ, か, ア…), in every voice.
SpeechGen.io. Commercial licence included in all plans.
VOICEVOX
Combined kana (きゃ, ティ…) and the site's former Japanese voices.
VOICEVOX:No.7 (No.7製作委員会), VOICEVOX:玄野武宏 (ViRVOX Project). Each voice's terms of use, which require this credit.
AivisSpeech
Japanese voices "Female" (morioki) and "Male" (にせ), chosen in the settings.
morioki (voice: もりおき, model: yuki), にせ (魔法プログラム). Each model's ACML 1.0 licence.
WanaKana
Romaji-to-kana conversion while typing.
© the WanaKana contributors. MIT License.
Reviews: FSRS (Free Spaced Repetition Scheduler), reimplemented for Kotojutsu with the default parameters published by the open-spaced-repetition project (MIT licence).
Authors, licences and links: Credits.
The practice tests
50 papers, ten per level, under exam conditions (timed) or as practice. Each one follows the written part of the JLPT in its official format since 2020: the same kinds of questions, in the same order, the same number of them and the same time. At N2 and N1, the single-sitting paper is split into two parts with the same total time. Listening is not included: the results tell you what score to aim for there.
| Level | Questions | Time |
|---|---|---|
| JLPT N5 | 43 | 60 min |
| JLPT N4 | 57 | 80 min |
| JLPT N3 | 74 | 100 min |
| JLPT N2 | 73 | 105 min |
| JLPT N1 | 69 | 110 min |
The first paper of each level can be taken without an account: JLPT N5 practice test.
Not official
JLPT (Japanese-Language Proficiency Test, 日本語能力試験) is a trademark of the Japan Foundation and Japan Educational Exchanges and Services (JEES). Kotojutsu is not affiliated with or endorsed by these organisations. The site's practice tests and level lists are original content, designed to practise the exam format: they are not official papers.
Report a mistake
- The “Report” button in the lessons, readings, practice tests, fill-in-the-blank sentences, flashcards, Kanjidex and dictionary: the report comes with the exact place of the mistake.
- Kotojutsu's Discord server, for a mistake, an idea or a question.
- The contact address, even without an account: [email protected].