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.
He is the instigator of this project.
There seems to be a mastermind behind the incident.
黒幕 emphasizes a hidden, manipulative figure pulling strings, whereas 仕掛け人 focuses on the act of initiating or setting up a scheme.
Standard spelling with okurigana.
Variant without okurigana; less common but still seen.
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'.