Fudou Jun is a highschool teacher and takes a trip with a group of students. While there, a group of martial artists staying nearby take a strange interest in the girls. These men are actually demons and after changing into their true form break into the cabin to rape the girls. One gets Jun and violates her.

She feels her soul being torn apart and transforms into Devilman Lady. With newfound powers and strength she kills all the demons and protects the girls from any further harm.

What are these demons and why did she turn into a hybrid of one? What does this mean for her and for the rest of humanity?