Shoko Nakagawa
The series is organized according to seasons and chapters, with each season thus far containing two chapters and each chapter having its own opening theme song. The first chapter of the series is , comprising episodes 1-27, and its opening theme song is , performed by MAKE-UP featuring Shoko Nakagawa. The second chapter is , comprising episodes 28-51, and features the opening song performed by . The second season begins the , comprising episodes 52-77, and with it a new opening theme titled performed by . The second half of season 2 comprises the from episodes 78-97, and uses the opening song performed by the band Cyntia.