Initially a battle racer in the Ogami Corps, trained under Dr. Ogami, he later finds enjoyment in regular racing with the Seiba brothers. Because of this, he decides to leave Ogami Labs, renouncing the anything-to-win attitude instilled by Dr. Ogami, and goes to live with Dr. Tsuchiya in his laboratory as an assistant. As a result, he also gradually changes in his personality, turning from an introvert into a more cheerful boy. Of all the other team members, J is the most skilled technician/mechanic, having prior experience with computers and machines while under Ogami's training. These skills are proven on many occasions, namely when he repaired the damaged Tridagger X to repay Ryo for damaging it in a previous race, when he helped Go design and build the Cyclone Magnum and when he designed the Proto Saber EVO. He appears to be best friends with Go.
* Cars: Proto Saber JB (JB Puroto Seiba JB), Proto Saber Evolution ( Puroto Seiba Evoryushon) * Birthday: December 14 * Blood type: AB * Height: 140 cm (roughly 4'7") * Weight: 32 kg (roughly 71 pounds) * Hobby: Gardening * Hometown: Japan