Kuufuku na Bokura

This is the beginning of the Human Farming Plan by zombies.

Humans are almost extinct, and zombie society is on the verge of a food crisis. Wataru, a zombie whose quirk is that he retained his human intelligence and emotions, cooked up a forbidden plan to achieve a breakthrough in the food crisis of his fellow zombies. His grand plan is: to look for surviving human males and females, get them to breed and begin farming humanity (food)!

However, the first surviving woman he encounters in his search is his ex-girlfriend, who he still has feelings for, even now!?

(Source: Shogakukan, translated)