(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

there's no accounting for taste

hoshuko, "supplementary studies school": school for overseas Japanese children

Synonym of 黄昏 (tasogare, “dusk; twilight”) / Synonym of 黄昏時 (tasogaredoki, “dusk; twilight”)

revisionism

"Historical kana usage", a prescriptive method of using kana to write Japanese. Devised in the Edo period by Keichū (契沖) and taught in schools until 1946, it aims to be etymologically faithful and reflects earlier stages of the language (Heian period and earlier).

(Buddhism) think on the power of Kannon

(informal) the lady doth protest too much; a girl's protests should not necessarily be taken at face value.