Yoichi Isagi (潔いさぎ世よ一いち, Isagi Yoichi?) is the main protagonist of the Blue Lock series. He is Rin Itoshi's greatest rival in Blue Lock.

Isagi is a second-year high school student, who played as a forward for the Ichinan High School football team. When he arrived at the Blue Lock facility, he became a member of Team Z for the First Selection. His main goal is to become the world's best striker.

After the Blue Lock Eleven played against the Japan U-20, Isagi is ranked as one of the top players 