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.

Kurimusubi Daisuke, a man fascinated by the complex zoology of monster girls in fiction, one day finds himself transported to a world full of them! When he encounters an arachne named Neya who needs his help...