The district of Shibugaya was once a vibrant hub of youth and chaos, but it has fallen into ruin after man-eating rabbits took over the underground network beneath the city. Into this dangerous wasteland steps a wolf-eared girl named Izuko, who is determined to find her missing senior, Higana, who disappeared while exploring the tunnels. By her side is a bunny-eared girl named Kyouka, one of the humanoid rabbits known as toga-usagi who are technically Izuko’s enemies. Despite their opposing sides, the two share overlapping goals and choose to fight together, forming an unlikely but fiercely loyal partnership.

The story follows their journey through the abandoned underground, where they confront both swarms of monstrous rabbits and the deeper mysteries behind the infestation. Kyouka is searching for a meteorite that she believes holds the key to curing a disease called Loneliness that afflicts her kind. As they delve deeper, Izuko faces the devastating truth about Higana’s fate, and Kyouka must pull her back from despair with sharp, forceful words that cement their bond. Supporting characters emerge, including Higana’s older sister Shiki, who provides tactical support, the art student Mari who inherits command from a defeated rabbit named Inaba, and the primary antagonist Yue, who harbors an obsessive aversion to devotion. The narrative balances intense action sequences with unfolding mysteries, gradually revealing the origins of the man-eating rabbits and the true nature of their affliction, while the emotional core remains the deepening trust and mutual dependence between Izuko and Kyouka.