Love Zombie: Romance of the Dead.

Shota is a high school student who is excited about love. His secret crush is on Hitomi, the best girl in the school. One day at lunchtime, Hitomi calls Shota out to her, and he does as she asks him to do, ending up losing his virginity. Still in disbelief, Shota decides to go to Hitomi's house after school that day. However, what awaits him at Hitomi's house is not a "sweet time for lovers", but a "cruelty-free eating". Hitomi has been infected with a zombie virus that is ravaging the streets of Japan...