Touka Minamori is a lonely college student with a secret lewd side whose life is upended when her childhood friend, Kokoha, recruits her to become a magical girl. To fight monsters known as "libidos," Touka must transform into Crystear, a process that requires generating mana through extreme public humiliation and sexual arousal. After a scandalous debut in her college classroom and a suggestive first battle, Touka is thrust into a world where her own modesty is the key to her magical power.