foil
Definition
A character who contrasts with another character, highlighting particular qualities; also a thin sheet of metal used for wrapping.
日本語 特定の品質を強調するために他のキャラクターと対照するキャラクター; または、金属を薄く切ったもの
Example
"In the play, the servant acts as a foil to the arrogant prince, emphasizing his humility."