YABAI

Real Japanese slang, one giant word at a time

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Textbooks teach a version of Japanese that stops at the classroom door. YABAI covers the other half: 308 real slang, internet, and fandom words, each presented on a card built around giant Japanese typography. Every word includes a meaning, a real example, and a vibe check that tells you whether it is safe to use, friends only, or something to be careful with. There is also a story behind the word, and when the origin is uncertain, YABAI says so instead of inventing one. The app was built end to end with AI agents in Claude Code, supports 13 languages, works offline, and skips the streaks, tests, and XP.