Choose a deck to study — or import your own (.csv)
Curated demo decks — one-click install. Bundled with the app (no live community backend in this prototype).
取り込み · Import Deck
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Export from Excel / Google Sheets as CSV. A header row is auto-detected; otherwise columns are read left-to-right. You'll map them on the next step.
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Map columns → lanes
Preview
設定 · Settings
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⚠ STRUGGLE DETECTED
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You've missed this unit 3× in a row.
Generating example sentences that reuse this word in new contexts is the fastest way to lock it in.
◷ FOCUS CHECK
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速い！
You're flying through these — are you still reading each one?
Mindless clicking doesn't build memory. Take a breath and look at the next word.
使い方 · How it works
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rikai (理解) is the most-optimized vocabulary trainer for serious learners — clean, offline, AI-assisted. Tap a section:
✦ AI features
A high-stimulation environment for acquiring words
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Language is acquired best in a high-stimulation environment — the more real signal around a word, the faster your brain keeps it. So every word in rikai carries more than a definition: a reading, its visual form, and a meaning you meet in several contexts rather than once on a flashcard.
Smart Sentence writes fresh examples woven from other words in your own deck, so the words reinforce each other instead of standing alone. Smart Definition opens the meaning up in the target language and your own. Practice Passage gathers the words you just studied into one short read. And when you add languages you already speak, rikai draws the connections between them — one concept seen from every side.
Images and pronunciation layers are coming next. The whole aim is one thing: an environment where acquisition happens the way brains actually learn — not memorising, but living with the words. These generate live when you're signed in (rikai's cloud AI) or on your own Gemini key; with no AI connected, a sample preview types into the background instead.
🌐 POLY · Multilingual
One concept, every language you're learning
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Import a CSV with extra language columns and each card carries the same concept in up to 4 more languages — on reveal they show together in a POLY grid. In My Decks, POLY SCAN runs rikai's AI over the deck once to surface cross-language connections and flag false friends (look-alike words that mean something different). A Pro feature; toggle POLY per deck in My Decks.
◇ Clean UI by design
Built to keep you learning, not fiddling
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Anki is powerful but cluttered. rikai hides the machinery: one word, one action. Scary controls live under Advanced in Settings, the header is just clean icons, and a Focus Guard stops you mindlessly clicking “correct” without reading.
Studying & grading
Reveal → grade → SM-2 schedules it
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Tap the word (or SPACE) to reveal reading, meaning & an example. Then: Don't Know (1) relearns it now & drops ease · Got It (2) grows the gap · Easy (3) jumps further. The rail shows session progress.
What is spaced repetition, actually?
Why the gaps grow — the forgetting curve
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Right after you learn a word, your memory of it starts to fade — the forgetting curve. Every time you recall it just before you'd forget, the memory resets stronger and fades more slowly, so the next review can wait longer. That's spaced repetition: instead of drilling everything every day, you review each word at growing intervals — tomorrow, then a few days, then a week, then weeks.
The grade buttons are you telling rikai how that went. Don't Know means the gap was too long — relearn it now. Got It means the interval was about right — grow it (e.g. +1d = see it again tomorrow, then longer and longer). Easy means it was too easy — jump the gap further ahead. Get a word right enough times and it stops taking your time at all. Read more on Wikipedia ↗
Quiz & Type modes
Stricter recall
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Quiz Mode shows ABCD meaning choices and auto-grades. Type mode has you type the reading in hiragana (auto-grades Easy/Don't-Know). Both live in the Modes menu (open the ☰ menu) — pick one anytime, or study with the plain reveal.
Flags, lists & decks
Organise & import
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Flag tricky cards with ⚑ (or F). Word List browses by state (incl. Often-Wrong & Flagged). In My Decks, import a CSV, browse the marketplace, or export a deck to CSV with your hardest words first.
Stats, settings & storage
Local & offline
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Statistics shows recall rate, maturity & most-missed words. Settings groups Appearance · Keybinds · Music & sound · Advanced (SRS tuning). Everything saves to your browser — works offline, nothing leaves your device.
About rikai
Who makes it & why
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rikai (理解) is an AI-native, offline-first spaced-repetition vocabulary trainer — AI example sentences, native pronunciation, and a POLY mode that trains several languages off a single concept. Built solo by Eric Torii, a design-led founder at Carnegie Mellon's Tepper School and an incoming PlayStation design intern. Quadralingual — fluent Mandarin, studying Japanese & Spanish — he designs the product and builds it with AI as his engineering team. Feedback? Email erictoriidesign@gmail.com.