Four free apps. Android, iOS, and web. Japanese kana through JLPT N1, English CEFR A1 through B2.
You didn't fail to put in the hours. You hit a wall that a generic app or a solo immersion attempt was never built to get you past. My Senpai finds that wall, in Japanese or English, and hands you the specific tool for it, from your first kana stroke or CEFR placement to fluency and beyond.
Not Duolingo. Built for skill acquisition, not daily streaks.
Not AJATT. Immersion with scaffolding, so you don't quit from overwhelm after six weeks.
Not just Genki. Grammar knowledge bridged to output you can actually produce under pressure.
⭐ 4.8 Kana Challenge rating · 170k+ dictionary entries in YoMoo
先輩 (senpai) means someone who started before you and turns back to help you catch up, not a teacher lecturing from outside the struggle, and not a gamified app selling you a streak. That's the role every product in this system plays. Whether the climb in front of you is Japanese kana or a CEFR English exam, the method is the same: find the specific wall you're stuck on, and hand you the tool built for that wall, not a generic one.
The answer changes everything about what you should do next.
Most kana approaches give you a chart and a quiz. That's not enough. Kana Challenge uses a 30-day spaced exposure structure. By day 30, recognition is automatic instead of something you have to stop and sound out.
Try Kana Challenge FreeUnderstanding grammar and producing sentences under pressure are two different skills. Fluency Tool's Echo Fluency system forces you to speak from session one: listen, shadow aloud, record, and compare against native audio. Speech recognition scores you in real time.
Try Fluency Tool FreeYoMoo takes authentic news, literature (青空文庫, Aozora Bunko), and JLPT passages and makes them readable at your actual level: automatic furigana on every kanji, one-tap lookups, and AI simplification that keeps the real content without the overwhelm.
Try YoMoo FreeRecognizing a word on a flashcard and producing its kana spelling from an English clue are different skills. Crossword's daily JLPT N5–N1 puzzles force the second one: type romaji, watch it convert to hiragana, and fill in the word from memory, not from a multiple-choice list.
Try Crossword FreeThis is the same output gap Japanese learners hit, just on the other side. Fluency Tool's Echo Fluency track runs the identical shadowing-and-recording loop, leveled to CEFR A1 through B2 instead of JLPT: listen to native audio, record yourself, get scored, repeat.
Try the English Track FreeNot sure which of the three you are?
It gives you a personalized study plan based on your current level, your goal (JLPT, travel, conversation, or reading native content), and how much time you actually have per day.
Take the Diagnostic Quiz →My Senpai takes the best of the existing approaches and fills the gaps that other methods aren't addressing.
Duolingo optimizes for daily active users. After a year, most users cannot hold a conversation or read a menu, in Japanese or English. My Senpai gives Duolingo graduates a credible upgrade path. It keeps the same study habit and applies it to skills that actually transfer. Read why people quit Duolingo for the full diagnosis.
Genki is genuinely useful for building a grammatical foundation. What it never supplies is the output training and authentic reading exposure that converts passive knowledge into spoken and read fluency. Fluency Tool and YoMoo are purpose-built for the post-Genki gap. The Grammar Library works alongside any textbook.
Refold's philosophy is correct. Comprehensible input works. The problem is friction. Most learners attempt pure immersion, hit a wall of incomprehensible content with no support, and quit within months. YoMoo delivers comprehensible input with the scaffolding (furigana, lookups, AI simplification) that makes it work for someone with an actual schedule.
AJATT works for under 5% of people. Only the ones who can restructure their entire life around Japanese stick with it. My Senpai delivers the same core insight (living inside the language accelerates acquisition) in a format compatible with a job, a family, and 45 minutes per day. The philosophy, not the extreme time demand.
Most CEFR-leveled English apps test recognition: pick the correct verb form, pick the correct preposition. Fluency Tool's Echo Fluency track has you shadowing native audio and recording your own voice from session one, the same production practice Japanese learners get, applied to the CEFR proficiency scale, A1 through B2.
Each tool is purpose-built for a specific structural problem. Start with one, or combine them for the full picture.
Solves: The Kana Wall
30 days of structured daily lessons that take you from zero characters to reading hiragana (ひらがな) and katakana (カタカナ) automatically. Spaced repetition is built into the schedule, not left for you to manage. Native audio, speaking practice, zero romaji.
Read kana in 30 days →
Solves: The Output Gap
Echo Fluency shadowing, SM-2 spaced repetition flashcards tied to grammar you are actively practicing, a full JLPT grammar guide (N5–N1 across 25 sub-levels), and pitch accent practice, all in one integrated system. Pick English during onboarding for the same system leveled to CEFR A1–B2 instead.
Start speaking Japanese or English →
Solves: Immersion Friction
Authentic news, Aozora Bunko (青空文庫) literature, and JLPT passages with automatic furigana, one-tap word lookups, SRS vocabulary review, and AI simplification that preserves real content without the overwhelm. N5 through N1.
Read real Japanese →
Solves: The Recall Gap
Type romaji and watch it convert to hiragana as you fill in real JLPT vocabulary, N5 through N1. Recalling a word's kana spelling from an English clue sticks in a way that recognising it on a flashcard doesn't. One new puzzle a day on the web; the app adds the full archive, offline play, and streaks.
Solve today's puzzle →
Every product is built on validated learning science, not engagement optimization.
Structured immersion pairs real, unmodified content with scaffolding, furigana and instant lookups for Japanese, native-audio comparison and CEFR leveling for English, so the content stays comprehensible instead of overwhelming. It sits between gamified apps like Duolingo, which cap out below real fluency, and pure immersion methods like AJATT, which most learners abandon from overwhelm.
Krashen's comprehensible input theory is the research basis for AJATT and Refold. It states that acquisition happens through exposure to real language slightly above your current level. YoMoo makes that practically possible from N5. The input is real, and features like furigana and one-tap lookups are the mechanism that keeps it comprehensible.
Skill acquisition research from DeKeyser and Anderson consistently shows that declarative knowledge, meaning knowing a grammar rule, does not transfer to procedural fluency without deliberate production practice. Fluency Tool's Echo Fluency cycle forces production at every session, whether the sentence is in Japanese or English, building the physical motor program for speech that reading a rule out of a textbook never builds on its own.
The SM-2 algorithm reduces the total review burden while maximizing long-term retention. The difference in our apps: flashcards in Fluency Tool are linked to grammar patterns you are actively shadowing, in Japanese or English, not a generic word list. Vocabulary saved from YoMoo articles is reviewed at intervals calibrated to actual forgetting curves, not arbitrary daily quotas.
A closer look at the screens you will actually use.
Use these in the browser to reinforce what you are practicing in the apps.
Paste any Japanese text and get instant grammar breakdown, furigana readings, and vocabulary lists. Useful after reading a YoMoo article you want to analyze deeper.
Guess the reading before the yen runs out. More effective for low-frequency kanji than flashcard review because it forces active recall rather than recognition.
Timed hiragana and katakana recognition practice. Good for isolating the handful of characters that keep slipping past you. No account needed.
Honest answers to the questions that come up most often.
Structured immersion sits between two extremes. Pure gamified apps like Duolingo keep you inside manufactured sentences forever, so there's a hard fluency ceiling. Pure immersion methods like AJATT work, but the friction is high enough that most people quit within months. Structured immersion uses real content with scaffolding that keeps it comprehensible at your current level, whether that's Japanese or English. Most learners get stuck on one of three walls:
My Senpai delivers this through Kana Challenge and YoMoo for the kana and immersion-friction walls in Japanese, and Fluency Tool's Echo Fluency and SM-2 flashcards for the output wall in either Japanese or English. The Japanese Learner's Map is the diagnostic framework that tells you exactly where you are and what to tackle next.
Duolingo optimizes for daily streaks. My Senpai optimizes for skill acquisition. In Japanese:
In English, Fluency Tool's CEFR-leveled track runs the same Echo Fluency production practice that Duolingo's English course substitutes with multiple-choice recognition. Read the full diagnosis in our article on why people quit Duolingo.
Yes, and this is one of the stronger use cases. A textbook or classroom course gives you grammar knowledge. Fluency Tool converts that knowledge into production ability through Echo Fluency shadowing, in Japanese or English, and YoMoo exposes Japanese learners to the same grammar patterns in authentic context. The Grammar Library covers the same N5–N3 range as Genki I and II with additional usage notes from real Japanese text.
Inside Fluency Tool, the Echo Fluency cycle runs the same way for Japanese or English:
The same sentence comes back at spaced intervals until your output is consistent, not just occasionally correct. This is closer to how pronunciation and fluency actually develop than passive listening or multiple-choice exercises. Learn more about the Echo Fluency methodology.
Yes. The Japanese Learner's Map is a free interactive phase-by-phase roadmap from your first hiragana stroke to JLPT N1 and beyond. Each node links to tool recommendations, honest advice about common mistakes at that stage, and what to skip. A 6-question quiz generates a personalized study plan based on your current level, your goal, and how many minutes you have per day. There is no English-track equivalent of this roadmap yet.
Hiragana first. It covers the grammatical fabric of the language, including verb endings, particles, and conjunctions, and it appears in virtually every sentence. Katakana is primarily used for loanwords and foreign names, which are easier to pick up once hiragana is automatic. Kana Challenge teaches in this order for that reason, introducing katakana through familiar loanwords once hiragana is solid. See the hiragana and katakana charts for a visual reference.
YoMoo layers three types of support onto real Japanese content: automatic furigana over every kanji so you always know the reading, one-tap dictionary lookups for any word without leaving the article, and AI simplification that rewrites the same article at a lower JLPT level without substituting toy sentences. An N5 learner can read an N3 news article through this system. Words saved from reading sessions feed directly into the SRS review queue at intervals calibrated for long-term retention.
Fluency Tool's English track runs on the same Echo Fluency shadowing and SM-2 spaced-repetition engine as the Japanese track, leveled to the CEFR proficiency scale (A1 through B2) instead of JLPT. It's built for ESL and EFL learners who already know English grammar rules but freeze up producing spoken sentences, the same output gap Echo Fluency addresses for Japanese learners. Pick English as your target language during onboarding to start it.
Longer articles that explain the why behind the method, for learners who want the reasoning, not just the steps.
Why pitch accent matters in Tokyo Japanese, how it works, and how to actually practice it, not just read about it.
Proven strategies for expanding your vocabulary systematically, without spending 90 minutes a day in Anki only to face a backlog that starts feeling like a debt.
The specific failure modes that cause Japanese learners to plateau after a year of Duolingo, and what to do once you hit the ceiling.
A small team in Tokyo, working on the gap between studying a language and being able to use it.
We've built and killed features that tested well for daily engagement but didn't move anyone's actual fluency. A streak counter should be a feature, not a product roadmap. Every product we ship has to answer one question first: does this remove a specific, named reason learners get stuck? No gamified busywork. No romaji shortcuts. No three years before you touch authentic content. That's what a senpai does: someone a few steps ahead who turns back to help, not someone lecturing from outside the struggle.
A small team of language learners and engineers based in Tokyo. We built Kana Challenge, Fluency Tool, YoMoo, and Crossword because the tools we wanted for our own Japanese study didn't exist yet, and we're building out Fluency Tool's English track for the same reason. Everyone on the team studies with the apps daily, so a feature that doesn't hold up in our own sessions doesn't ship.
Questions, feedback, or something broken? We read every email.
Contact the Team