One year after the Demon King’s fall, Belphegor, a former officer of the Demon King’s army, is living a lazy, hedonistic life. Unable to stand it anymore, the strategist Media gives him an order:

“Belphegor, go kill the Hero.”

Reluctantly heading to the human world, Belphegor waits for a chance to assassinate the Hero, only to stumble upon the Hero’s secret by accident… the Hero is not a man, but a woman?!

After learning the Hero’s secret, Belphegor proposes a deal, claiming he can lift her curse, and the two begin an uneasy journey together.