J trained as a battle racer under Dr. Ōgami, conditioned to win at any cost with destructive tactics. During the Tokichi Cup, he raced the Proto Saber JB, equipped with a remotely controlled air brake system used to damage opponents. Defeated by the Seiba brothers and witnessing traditional sportsmanship, he renounced battle racing, destroyed his remote controller, and joined Dr. Tsuchiya's laboratory as an assistant. This departure from Ōgami's philosophy began his integration into the TRF Victorys team.

His Ōgami-honed technical expertise made him the TRF Victorys' most skilled mechanic and technician. He proved this by repairing Ryo Takaba's Tridagger X after damaging it earlier, co-designing and building Go Seiba's Cyclone Magnum, and later creating his own Proto Saber Evolution. This machine featured the Dolphin System and served as a support-oriented car during the World Grand Prix (WGP), reflecting his shift to cooperative racing. He maintained a particularly close friendship with Go.

Personality-wise, J evolved from quiet and introverted to more cheerful and socially engaged after joining TRF. He developed a strong sentimental attachment to his machines, visibly distressed when the Proto Saber Evolution faced danger or damage during races, underscoring his commitment to ethical racing and team dynamics.

In the movie *WGP Bōsō Mini Yonku Dai Tsuiseki!*, J joined the TRF Victorys in pursuing the out-of-control Gun Bluster XTO after it was manipulated by a malicious chip, showcasing his role as a dedicated team member in crisis.

Later media, including racing games, spin-offs, and *Return Racers*, consistently depicted his machines as well-balanced, with his legacy persisting through technical contributions and his foundational role in the TRF Victorys' ethos.