いつか天魔の黒ウサギ 心移りの登校日 ~すくーる·あてんだんす·でぃ~

"Kokoro Utsuri no Toukoubi ~School Attendance Day~" is the 13th episode of the anime "Itsuka Tenma no Kuro Usagi" (A Dark Rabbit Has Seven Lives), but it was not broadcast on television. Instead, it was included as a bonus DVD with the limited edition of the ninth novel volume. This episode takes place after the main anime storyline and mainly focuses on a comical situation where characters switch bodies due to an accident. The body swap between the protagonist Taito Kurogane and other main characters leads to a series of hilarious scenes. Notably, the protagonists from "The Legend of the Legendary Heroes," Ryner Lute and Ferris Eris, make a guest appearance in this episode and battle Kurenai Hinata, marking the only crossover between the two series. Furthermore, this episode includes many fan-oriented parody elements and various interesting interactions between the characters, making it an unmissable episode for fans of "Itsuka Tenma no Kuro Usagi."