Yae is bored with normal sex. She wants to experience something new, so she half-jokingly asks her genius brother Watase if he could create a body swap device. To her surprise it turns out that Watase already has such a device. Yae immediately decides to try it out...

Included one-shots: Play Hooky, Test-go no Totteoki, Mephistopheles: Lydia Aburachenko-hen