top secret

serious, earnest / honest

serious / earnest

(humble) meet

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

sole of the foot

An underhanded trick. / A lifehack.

(literary, rare) here

(painting) the application of silk as a screen on metal foil, or the metal foil in that application

Synonym of 屋根裏 (yaneura, “attic”)