The Corpse That Roams in the Night: Shirotabi
Shirotabi (Episode 9)
Shirotabi was a rabbit that was cared for by the school pet keeper, Mioh. After its death, Mioh decided to bring Shirotabi back through a black magic ritual. The spell worked, but in the other side Shirotabi was put into a curse where it turns into a killer demon every night. Mioh tried to stop Shirotabi, but realized Shirotabi didn't even recognize her. It was up to Satsuki and the others to convince Mioh that Shirotabi's place should be with the dead, and so Mioh agrees. Mioh broke the spell, and Shirotabi remained dead forever. It appears in episode 9 and makes a cameo in episode 20.