noun
A person who always agrees with a superior or authority, often to gain favor or avoid conflict. Carries a negative connotation of lacking independence.
彼は上司のイエスマンで、自分の意見を言わない。
He is a yes-man to his boss and never expresses his own opinion.
イエスマンばかりでは組織は成長しない。
An organization won't grow if it's full of yes-men.