Suou is just a normal highschool student. One night, she dreams about a red-haired demon girl... who shows up the next day in the middle of class and "claims" her as her property.

Hida Kizuna visited the strategic defense academy Ataraxia based from the call of her big sister where he encountered the girl who operated the magic armor <Zeros>, Chidorigafuchi Aine. Aine suddenly took of...