Minato Katana, a 20-year-old university student in Shibuya with an obsession for web novels, discovers an ancient book titled The Realms of Eternity during a fateful midnight encounter. The mysterious tome harbors a summoning ritual that Minato accidentally invokes, dragging the Demon Lord's curvey and broken daughter directly into his cramped apartment. To his supernatural roommate, he's merely a juice tank—a living resource to exploit without mercy. Trapped in an unexpected arrangement between a curious human and a dangerous demon, their cohabitation ignites a storm of fantasy, action, and forbidden passion. As ancient secrets unravel and supernatural forces collide, Minato discovers that some summonings were never accidents. In this tale where desire and darkness intertwine, one man learns that the price of curiosity is far more intoxicating than he ever anticipated.