After saving a fantasy world by vanquishing a Demon Lord, the young hero Hinata Sunohara is returned to Earth to resume his quiet high school life. His peace is short-lived, as a former adventuring companion, the dark elf sorceress Mariabelle, uses her magic to cross dimensions and follow him home. She arrives with a confession of obsessive love and a determination to stay by his side forever, instantly moving into his apartment. Now, Hinata must navigate a chaotic cohabitation with a beautiful but dangerously possessive woman who becomes violently jealous of any female classmate, like the shy Sakura Mochida, who shows him attention. The story revolves around Hinata trying to reconcile his innocent, conventional view of romance with Mariabelle’s relentless, pressure-filled, and often seductive pursuit of him.

The primary setting alternates between Hinata’s small apartment and his modern Japanese high school, as Mariabelle adapts to contemporary society while bringing her otherworldly sensibilities with her. Notable narrative arcs include the arrival of former party members, such as the priestess Cecile and the catgirl Mei, who come to observe or retrieve Mariabelle, leading to further complications. The story also explores Mariabelle’s backstory, including the appearance of her emotional mother, Miranellia, who attempts to separate the couple out of fear her daughter will suffer the same heartbreak she did after loving a mortal human. Across twelve short episodes, the central conflict remains Hinata’s gradual acceptance of Mariabelle’s intense and obsessive form of love, which serves as the engine for a series of erotic romantic comedy situations.