Since childhood, Chihiro Furuya has been obsessed with zombies, dreaming of having an undead partner. His fascination becomes practical when his cat, Baabu, is hit by a car, prompting Chihiro to create a resurrection elixir in hopes of reviving the pet. While experimenting, he meets Rea Sanka, a wealthy girl who releases her frustrations about her oppressive home life by shouting into an abandoned well. After bonding with her, Rea encourages Chihiro to continue his work, and he eventually succeeds using poisonous hydrangeas from her family’s garden.
Unaware that the potion works, Rea drinks it hoping to end her suffering, believing it will kill her. Instead, the potion’s magic interacts with a fatal accident, causing her to rise as a zombie. With Chihiro’s help, she tries to navigate her new existence. Though this might seem perfect for a boy seeking a zombie girlfriend, life in Sankarea becomes increasingly strange as Chihiro must manage Rea’s unusual new appetites and the unexpected consequences of her transformation.