Sankarea

Briefly about Sankarea manga:

Chihiro Furuya is a high school student fascinated with zombies. He counts them among his hobbies, including collecting their videogames and other zombie-related paraphernalia. When his pet cat dies, Chihiro uses an old manuscript to try to resurrect it. However, the only person willing to test his spell—and serve as a test subject—is a girl named Rea Sanka, who is trying to commit suicide. She swallows a potion made from the toxic Hydrangea macrophylla flower and dies. In an ironic twist her desire for death gives her life and she becomes Chihiro’s zombie girlfriend.