Jagi stands as one of Ryuken's four adopted sons trained in Hokuto Shinken. Significantly older than Kenshiro, he seethes with resentment over Ryuken's choice of Kenshiro as the art's successor, openly challenging the decision and branding Kenshiro the weakest brother. Learning unsuccessful successors face dire consequences like shattered fists or erased memories, Jagi confronts Kenshiro. He demands Kenshiro renounce his position, brandishing a firearm. When Kenshiro refuses and tries to leave, Jagi escalates by physically assaulting him with the gun. Kenshiro retaliates, disarming Jagi and unleashing a rapid series of strikes that slam him into a wall. This attack permanently disfigures Jagi, causing his head to bulge grotesquely and tearing out his hair.

Though Kenshiro spares Jagi's life, he dismisses him as unworthy of Hokuto Shinken. Jagi flees the dojo vowing revenge and threatening future murder. His Hokuto Shinken skills are explicitly inferior to Kenshiro's, a disparity underscored by his reliance on weapons during the fight rather than martial prowess.

Earlier at the dojo, Jagi trains alongside his brothers. During a sparring session, he displays aggression by attempting to kick Yuria's barking puppy. Kenshiro intervenes, highlighting their animosity predating the succession conflict. Jagi's combative nature shows in his eagerness to instigate conflict, such as bursting in to announce Kenshiro's selection to Raoh and Toki. He predicts Kenshiro's mercy would prevent him from killing Jagi despite Jagi's murderous intent.