noun
underhanded person; Machiavellian schemer
Refers to someone who uses cunning, behind-the-scenes tactics, often in politics or business. The term originally comes from judo, where 寝技 (newaza) are ground techniques, implying a person who works from a hidden or disadvantaged position.
彼は政界の寝業師として知られている。
He is known as a behind-the-scenes operator in the political world.
あの寝業師に騙されないように気をつけろ。
Be careful not to be deceived by that schemer.
陰謀家 explicitly means 'conspirator' and focuses on plotting, while 寝業師 emphasizes cunning manipulation in a broader sense, often in organizational contexts.
Compound of 寝業 (newaza, 'ground techniques' in judo) and 師 (shi, 'master' or 'specialist'). The figurative meaning derives from the idea of a judo practitioner who excels at ground techniques, metaphorically extended to someone who operates skillfully from a hidden or disadvantaged position.