private life, personal life

illegitimacy (being born out of wedlock)

a privately-owned ricefield, especially one under the historical 律令 (Ritsuryō) system

personal grudge

Kyūjitai form of 私鉄 (“private railway”)

a monarch butterfly

Used other than figuratively or idiomatically: see 一 and 本 (one thing) / Short for 一本勝ち (ippon-gachi, “winning in one blow”).

a comic book, a cartoon book

hardcore pornography; 'underground' pornography showing uncensored genitals. Technically illegal in Japan.

banned book