(monarchy) a cadet branch of the Japanese imperial family, established upon the marriage of a 親王 (shinnō, “prince”); it has a distinct title called 宮号 (miyagō)

to study / to learn

history / the study of history

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

historian

study of history

(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

oral history

historicism

"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).