underhanded dealings

underbelly of society

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

actual and hidden

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

the futokoro, the pocket-like space within the front of a kimono above the obi / the inside of the futokoro / the inside of one's heart or mind

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

sole of the foot

tie to, lash to, fasten onto

stain, blot, smudge