everything

(slang) Alternative form of 彼氏 (kareshi, “boyfriend”)

everyone, one and all

oral history

historicism

historian

(Internet slang, especially anime and manga fandom) events or things from the past which one wants to whitewash/erase from history (due to it being embarrassing, poorly received, etc.); dark past

study of history

historic, historical / already-happened, past / former, old, traditional

research & development; R&D