scary face; angry look; grim expression
Describes a facial expression that looks frightening, angry, or stern. Often used when someone's face unintentionally looks scary or when they are deliberately making a threatening face.
He glared at me with a scary face.
That teacher has a stern face, but is actually kind.
Compound of 怖い (scary) and 顔 (face). The exact historical derivation is straightforward; the phrase is a common collocation in modern Japanese.