(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

妊娠: pregnancy, conception

深夜: midnight / 新家: new house

信也, 真或, 真矢, 真也, 慎也, 伸也, 晋哉, 申也: a male given name / 真哉, 信哉, 紳矢: a male given name / 新屋, 新谷: a surname

心理: mentality / 真理: truth / 審理: trial

都心: city center, urban center, heart of a city / 兎脣, 兎唇: harelip, cleft lip / 妬心: jealousy

寝室: bedroom / 心室: (cardiology) ventricle

新任: newly appointed, newly elected / 信任: confidence / 親任: imperial appointment / 信認: acknowledgement