Kuro, a black cat, was once a god of fortune but has fallen and become a vengeful god. The only way for her to regain her former status is to curse seven generations of the Nishikori bloodline. She has already cursed six generations and is nearly free, but she must ensure the seventh generation is born. That means finding a wife for the current Nishikori heir, Kotaro Nishikori, a high school student who lives alone while his parents are away. Kotaro is tragically unpopular, partly because a lingering curse has made his love life a disaster. Yet he insists that the only woman he wants is Kuro herself.

Kuro can take human form, appearing as a cat-eared girl, and Kotaro has been searching for her ever since he saw her at his grandfather's funeral. He recognizes her the moment she transforms, but Kuro is a god and cannot bear a human child. Thus she tries to set him up with his childhood friend Hikari Sawa, a kind, beautiful, and popular girl who has always loved Kotaro. Hikari is unaware that Kotaro's heart belongs to Kuro, and Kuro herself begins to develop feelings for him, creating a tangled love triangle.

The story follows Kuro's frantic attempts to make Kotaro fall for someone else, while Kotaro remains stubbornly devoted to her, and Hikari grows suspicious of the bond between them. As the three live under one roof, their relationships deepen and shift. Kuro's old friend, the god of fortune Nami, reveals that it is possible for gods and humans to have children, but that realization only complicates things further. The manga builds toward a confrontation between Kuro and Hikari, who must decide between friendship and love. The narrative ends with the three characters resolving their feelings in a final volume that brings the curse and the romance to a close.