|“||When Onigashima-san gets angry she turns into a de-.||”|
—Volume 9, Chapter 121
|Full Name||Onigashima Akako|
|School||Itan Private High School|
|Year/Course||1st year Class 1 (Former)|
|Manga Debut||Chapter 19|
Akako has short hair with one strand that sticks out at the top. She also has a fang on the left side of her mouth. She is most often seen wearing the Itan school uniform. The ends of her hair spike up like horns when she is mad.
Akako originally shows up in chapter 19 to play Saitou with Komi but later has a larger role in chapter 121 "An Iron Club for a Demon in which Tadano takes note of how her day is going. She is shown to be generally easy-going but can become very annoyed at minor inconveniences. One of the things she is upset by throughout the day is the tangling of her headphones which Komi untangles for her. As thanks, Akako takes Komi, Tadano, Yamai, and Najimi to a batting center where she shows she is very skilled at batting.
- Her name Onigashima Akako (おにがしま, あかこ) means Red Girl from Oni Island which is a reference to the tale of Momotarou.