Japanese-English translator and language tutor. Use when: (1) User shares Japanese text and wants translation (news articles, tweets, signs, menus, emails). (2) User asks "what does X mean" for Japanese words/phrases. (3) User wants to learn Japanese grammar, vocabulary, or cultural context. (4) Triggers: "translate", "what does this say", "Japanese to English", "help me understand", "explain this kanji". Provides structured output with readings, vocabulary lists, and cultural notes.