|Manga Debut||Chapter 171|
Full Open (尻全開 (フル・オープン), Furu Ōpun), also known as Demon Butt (鬼の尻, Oni no Shiri, lit. "The Butt of Demon") is a special ability possessed by Misaki Rindou.
Misaki Rindou's butt is called "Demon Butt". Her butt is able to perform photosynthesis. By exposing her butt under the sunlight, Misaki takes a very deep breath for cellular respiration. She then farts the oxygen out of her butt. By doing so, Misaki can evolve her butt into that of a smiling demon face, obtaining a large amount of strength. While in her "Demon Butt" mode, her skin turns darker. However, there are downsides of this ability. For example, when Misaki is driven away from the sunlight, or with attempts of blocking her butt from getting exposed by the sunlight. As a result, her skin returned to normal.