(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

pedestrian-only street, pedestrian mall

Kyūjitai form of 太平天国 (“Taiping Heavenly Kingdom”)

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).

By teaching, we learn. Docendo discimus.

revisionist

If one learns without thinking, one will be lost in his learning. That is, if one does not think about what one learns, he will not arrive at the truth of it.