YABAI

Textbooks teach Japanese that stops at the classroom door. YABAI is the other half: 308 real slang, internet and fandom words, each on a card built around giant Japanese typography. Every word has a meaning, a real example, a vibe check (safe to use? friends only? careful?) and a story — and when the origin is uncertain, it says so instead of inventing one. Built end to end with AI agents in Claude Code. 13 languages, works offline. No streaks, no tests, no XP.