Kengo is a new friend Wataru meets when he and the girls attended school in Tokyo after Yokai Academy closed for repairs following the disasterous school festival. He made his debut when he befriended Wataru immediately and upon learning of their love for music, Kengo invited Wataru to join his band the IKEMENS. He even recruited Shizuka to play the drums while Wataru learns to play the bass. As the band needed a lead singer, Megumi took over as bass player and Wataru sang for the band for their first lead gig. Kengo would be unaware of the identity of the Kamen Riders for awhile. During summer vacation, he worked at his aunt's beach house and inn with Sun Otonashi. He fell in love with the girl and protected her from an evil male Siren. Even when learning the truth behind her identity, he did not reject her. They started dating soon after. He was later seen as a guest in Wataru's wedding with his girlfriend.