top secret

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”)

(sometimes offensive) part of Japan adjacent to Sea of Japan

(Internet slang) secret personal account (on social media, especially Twitter and Instagram (finsta), as opposed to one's openly used account)

(music) syncopated beat, an accented part of a rhythm marked by syncopation