Ritsuko imposes an intense dancing routine on Ryügü Komachi to prepare them for an upcoming secret concert, much to the group's displeasure. While checking out Ryügü Komachi's fan letters, the Producer finds one with a picture of Ritsuko when she was an idol, sent by a fan of hers with the nickname "Petit Bellpepper", much to her embarrassment. Upon learning Azusa won't be able to perform due to mumps, Iori and Ami come up with the idea of having Ritsuko take Azusa's place in the concert, since she's the only one who knows the song and dance routine. As the Producer and Miki support the idea, Ritsuko reluctantly attends dance training with Iori and Ami, allowing them to take advantage of it and get back at her...