After Kengo reaches a dead end in finding out the identity of the mysterious black suited Kamen Rider, confirming him not to be of his father's design, Ms. Sonoda introduces a new transfer student named Ryusei Sakuta whom Gentaro offers to help despite both Ryusei's and Ms. Sonoda's wishes. Soon after, Gentaro hears of a rumor of a cat monster attacking students with good grades.