Rei, a poet, contracts a zombie infection during a plague in Japan. Authorities confine incurable cases within walled enclaves but provide treatment for individuals like Rei who show recovery potential. Yūna is Rei's younger sister, and Rika serves as their physician.

When zombies breach the containment walls, Rika partners with a smuggler named Takeshiba to orchestrate Rei and Yūna's overseas escape for advanced treatment. Rei declines this opportunity, choosing instead to return to a distant, isolated homeland to die. The siblings embark on a journey across a ravaged landscape, encountering grotesque and unsettling phenomena.

Rei's poetic background shapes their perspective on the decaying world. This odyssey defines Rei's arc—a deliberate choice to confront death in a place of familiarity amid overwhelming desolation.