Jashin-chan, a devil from Hell was abruptly summoned to the human world by Yurine Hanazono, a stoic college student who lives in a run-down apartment in Jinbocho. They're forced to become roommates since Yurine doesn't know how to send Jashin-chan back. But according to Jashin-chan, she could return by killing Yurine, so she takes action...?! A viperous roomie comedy that keeps you on your toes!

The age of the demons has begun. Dr Faust has foreseen this rise of evil. Unfortunately, he is near death and is unable to personally battle this upcoming threat. Faust entrusts a young boy, Shingo Yamada, to take the responsibility of ridding the Earth of this new evil presence. Faust finds a birthmark on Shingo's forehead that signifies that he is the chosen demon fighter. Faust summons from hell what may be humanity's only hope of surviving: a less than enthusiastic devil named Mephisto rises. After signing a pact in blood to save humankind, Shingo and Mephisto set out to battle the supernatural world.