expression, i-adjective
black-hearted; scheming; malicious
Describes a person who appears kind on the surface but harbors ill intentions or selfish schemes. Often used to criticize someone's hidden nature.
See also: 腹黒い
彼はいつも笑顔だけど、腹が黒いから気をつけたほうがいい。
He's always smiling, but he's black-hearted, so you'd better be careful.
あの政治家は腹が黒いとよく言われている。
That politician is often said to be scheming.