In the middle of their battle with Lucifero, a portal opened up beneath Asta and Liebe, sending them to another world. They soon find themselves stranded on Tenrou Island, and had been living there for some time. Then, one day, they encounter a young man with black hair who had been stricken with a terrible curse that robs all around him of their lives. Asta and Liebe become well acquainted with the man he taught the devil and Magic Knight about how the world works. Days later, the trip quickly find themselves in the middle of a battle between the world's strongest guild and a guild hellbent on retrieving Asta and Liebe's new friend. Which side will the young devil host take?