executor; enforcer; person in charge of implementation
Refers to someone who carries out a plan, order, or legal decision. Can be used in business, legal, or organizational contexts.
He was appointed as the person in charge of implementing the project.
The court appointed an executor of the will.
executioner
Compound of 執行 (しっこう, 'execution, enforcement') and 人 (にん, 'person'). The exact historical derivation is uncertain, but the word follows a standard pattern for forming agent nouns.