A-kun (17) no Sensou - I, the Tycoon?

Onodera Goushi, an unassuming high school student, finds his life forever changed when he's rescued from a life-or-death situation by a mysterious girl named Honoka, who transports him to the "Demon Nation", a world inhabited by supernatural beings. There, he encounters the enigmatic Mahou, an anime otaku whose passions and quirks are a far cry from the typical demon. As Goushi navigates this unfamiliar realm, he must confront the challenges and contradictions of his new surroundings, all while trying to understand the motivations of his unlikely ally, Honoka.