ナンバー1

Top detective of the World Detective Organization.
He is almost never seen in public and his true identity is unknown. The detectives refer to him only by the nickname Number One.
He gives orders to the detectives in Kanai Ward via a direct line from headquarters.
[From official website

He is eventually revealed to be a body double for the actual Number One. The body double is killed during a bombing on the World Detective Organization headquarters.