noun
instigator; mastermind; person behind the scenes
Refers to someone who sets a plan in motion, often secretly or indirectly. Can be used in both negative (schemer) and neutral (organizer) contexts.
彼がこのプロジェクトの仕掛け人だ。
He is the instigator of this project.
事件の裏には仕掛け人がいるらしい。
There seems to be a mastermind behind the incident.
Compound of 仕掛け (しかけ, 'setup' or 'device') and 人 (にん, 'person'). The exact historical derivation is uncertain, but the word literally means 'person who sets things up'.