Masato Kusaka is a member of Ryusei School who was apparently absent from the reunion, but signed the autograph card. He is the only Ryuseiji who was capable of wearing the Kaixa Gear without disintegrating afterwards and as such is the Gear's primary wearer. As a child, Masato was often bullied and alone with only Mari Sonoda as his friend. In time, Masato came to love Mari, though his feelings were not reciprocated back, and results to unethical means to remove any he views as competition or a threat to Mari's happiness like Takumi.