The Living Dead!

Aoyama Keita had a crush on his classmate Haida Monako, but he was too shy to tell her. One day, when Haida suddenly passes away, he is finally able to confess to her through a letter he places at her funeral. Little does Keita know, she returns as a zombie and blackmails him into letting her stay with him with the threat that she will tell everyone about the love letter if he doesn't. Now Keita has to hide Haida from his parents, classmates and the outside world because everyone else thinks she is dead. To make matters worse, as a living dead, she craves flesh from time to time and Haida doesn’t care if it comes from Keita… (Source: MangaHelpers)