Hiroshi is a career race-car driver.
He is first seen in the film having lunch near a lake with his friend Goro Ibuki whose brother Rokuro plays in the water. Their afternoon is cut short by an earthquake that drains the lake of its water. Hiroshi drives the brothers home, only for them to discover that Goro's laboratory has been ransacked. Hiroshi sees the culprits and gives chase, but is fended off when the attackers drop an incendiary device on the road. later on, the Seatopians return to Goro's home and knock out the Ibuki brothers, and also tie up Hiroshi. Hiroshi awakens and the Ibukis are gone, leaving Hiroshi to ask the guard about the Seatopians' plan. After gaining this sensitive information, Hiroshi broke the chair he was tied to, K.O.'d the guard, and left to find Goro and Rokuro. Hiroshi discovers a truck with a large container on its bed, and deduces that his friends may be inside. Megalon emerges and the truck tips over, spilling the Ibukis into a ditch. Hiroshi approaches the military with his information on the Seatopians' plans. the military then lends Hiroshi and Goro a jeep to recapture Jet Jaguar's main control console. After the defeat of Megalon and Gigan, H iroshi walks away with the Ibukis and Jet Jaguar.
- There is a long standing rumor that Hiroshi is homosexual and is in a romantic relationship with his friend, Goro Ibuki.