Issei Isagi

Issei is kind, calm and supportive of his son's ambitions. He does not pressure Yoichi toward a conventional career or dismiss professional football as unrealistic, instead allowing him to pursue the opportunity offered by Blue Lock.

His support is understated. Issei does not need to understand every detail of elite football to recognize how seriously his son treats it.

He shares this parenting approach with Iyo, creating a home environment in which Yoichi's increasingly ambitious goals are met with encouragement rather than resistance.

Issei is not established as a competitive footballer and possesses no canonical footballing weapon or technique.

His role exists outside Blue Lock's competitive structure. The support he and Iyo provide gives Yoichi a family environment that contrasts with the intense pressure and unstable relationships experienced by several other participants.

Issei appears at the beginning of the series around the time Yoichi receives his invitation from the Japan Football Union. He and Iyo allow their son to pursue the unusual training opportunity rather than preventing him from entering Blue Lock.

He later attends the Blue Lock Eleven versus Japan U-20 match, where he sees Yoichi compete publicly on a much larger stage than his previous high-school football.

Issei remains a minor supporting figure, but his appearances provide continuity between Yoichi's life before Blue Lock and the increasingly public football career that develops afterward.

Yoichi Isagi is Issei's son. Issei has supported Yoichi Isagi's ambition to become a footballer since childhood.

Iyo Isagi is Issei's wife and shares his supportive approach toward their son.

Yuu Bachira meets Issei during the U-20 match and thanks him and Iyo Isagi for Yoichi Isagi playing football alongside her son, Meguru Bachira.