Seniors and juniors. In the near-future demon city of Tokyo, the anti-demon ninja Mizuki Yukikaze, who protects humans from monsters and demons, volunteers to join a stealth mission with his senior, Rinko Akiyama, in order to rescue his missing mother. Akiyama Rinko and Mizuki Yukikaze are seniors and juniors. Akiyama Rinko, Ai Meili's backbone before she appeared, has skills like Wind Cut, Meteor, and Jump/Space Crack.