(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

液滴: drop (of liquid)

the very same person

Synonym of 新撰万葉集 (Shinsen Man'yōshū): a 私撰和歌集 (shisen wakashū, “privately-compiled waka anthology”) in two volumes in which the poems are completely written in 万葉仮名 (man'yōgana)

兀:

木屑: / 忽: one hundred-thousandth / 笏: / 骨: remains, ashes; knack

北: north

past tense form of きる / past tense form of くる