Kuraishi Yuu manga
Aoshima Hitoshi is a second year student in high school, who wishes he had a girlfriend. One day he wakes up for an unknown reason 10 years in the future, and he is married to the prettiest girl in school, Wagatsuma Ai! How has their relationship grown from mere acquaintances to husband and wife!?
What can you do when you get mistaken for murder? Nothing. You go to prison. Lucky you, your inmates are some of the biggest cutthroats in the prison. Seriously you are lucky. Expecially when zombies attack.