(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

to hide, to conceal

that which is hidden / that which is protected from outside / (clothing) pocket

oneself / first-person pronoun: I, me (often shows the speaker's lower position in a hierarchy than the addressee) / (Kansai) you

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend

black (color) / (go) a black stone; the person who plays black stones / a 女房詞 (nyōbō kotoba, “woman's word”) for 鍋 (nabe, “pot, pan”) or 釜 (kama, “pot, kettle”)

history / the study of history

one shouldn't bury one's head in the sand while leaving one's bottom exposed