A demon summoned from hell decides he doesn't care enough to save humanity, so a kid has to drag him into it anyway. The whole thing moves like a fever dream where nobody's actually sure what they're fighting or why it matters. By the end you realize the real horror isn't the demons, it's watching a reluctant devil and a powerless kid figure out they're stuck with each other.
A dying sorcerer recognizes the mark of destiny on an ordinary boy's forehead: Shingo Yamada is humanity's last chance against a rising tide of demonic forces. With his final act, the old mage makes an impossible bargain, pulling a reluctant devil named Mephisto from the depths of hell itself. Bound by blood pact, this mismatched pair must now stand against supernatural horrors threatening to consume the world. Shingo is thrust from childhood into a war he never asked for, while Mephisto grumbles about being dragged into humanity's problems. Their only advantage is each other, though trusting a demon to save mankind seems like terrible odds. What unfolds is a collision of worlds where a scared kid and a cynical devil discover they might be the only thing standing between existence and oblivion. Dark forces close in from all sides, and time is running short. Mephisto's power alone won't be enough; Shingo will have to find courage he didn't know he possessed to survive what comes next.