Manga My Wife Is Wagatsuma-san / Wagatsuma-san wa Ore no Yome
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!?