This is the 8302nd most frequent Japanese word.
張本人
"張本人" means "main culprit" or "primary instigator."
Used to denote the individual directly responsible or the principal culprit in a certain situation or event.
彼が事件の張本人だと判明しました。
It was found that he is the main culprit of the incident.
Indicates the person who is the principal cause or instigator of the problem being discussed.
問題の張本人は笑いながら部屋を出ていった。
The main party involved in the problem left the room laughing.
Here '張本人' is used to attribute credit to someone as the main contributor or leader in creating an enjoyable situation.