Sentence Questions
Multiple-choice questions on real sentences: pick the particle, form, or word that makes the sentence work.
Live in Beta
Adaptive Japanese Learning
Build your Japanese with practice that adapts to what you know.
For JLPT N5 learners who already know kana and some basic Japanese.
Built by Jason Kobayashi in Tokyo
- Mind Map534conceptsGrammar, vocabulary, and kanji
- Study Content4,000+A variety of content types, with more added over time.
- Learning ModelAdaptive EngineMatches your level and focuses practice on what you're ready to learn next.
Why Mastermind?
Tracks Japanese at the Concept Level
Practice is linked to specific grammar, vocabulary, and kanji concepts, so your results can show which ones need more work.
Review Adjusts as You Learn
Your results and the time since your last review help decide what comes back next.
Short Sessions Count
Study at your own pace. Mastermind keeps track of your progress.
Monitor Your Progress
Progress bars on the Study page show how much of the material you have covered. The Mind Map shows 534 concepts in 3D or 2D, with color estimating how solid each one is from the practice you record in Mastermind.
Overall28%
Today60%
Kanji
Particle
Adverb
Verb
Grammar
Noun
Adjective
Practice Japanese with Mastermind
Mastermind offers a variety of Japanese practice activities.
Vocabulary & Kanji Cards
Reading, meaning, and an example for a word or kanji, with a quick self-rating that feeds your schedule.
Listening
Short dialogues and audio-first cards: listen, understand, then check.
Sentence Building
Arrange Japanese pieces into the right order to build the sentence. Appears once the words in a sentence are already familiar to you.
Reading Stories
Short N5-level stories with comprehension checks. Stories unlock as your vocabulary grows, so early on you may not see one yet.
Kanji Writing
Draw supported kanji by hand; recognition runs locally in your browser.
Speaking Practice
Say Japanese words and phrases aloud, then check what your browser understood.
Product Facts
- Practice types: sentence questions, vocabulary and kanji cards, listening, sentence building, reading stories, kanji writing, verb focus, and speaking practice.
- Full disclosure: Mastermind is built with AI under the direction of Jason Kobayashi. He draws on over 20 years of web development experience and over 30 years of studying Japanese to run the site and improve it over time.
© 2026 Jason Kobayashi