leader; prime mover; originator
Refers to a person who takes the lead in an initiative, movement, or project; emphasizes active guidance and driving force rather than just a figurehead.
He was the prime mover behind the reform movement.
As the project leader, she brought the team together.
Compound of 主導 (shudō, 'leading', 'taking the initiative') + 者 (sha, 'person'). The word 主導 is itself a combination of 主 (shu, 'main') and 導 (dō, 'guide').