Kuufuku na Bokura

Humans are nearly extinct, and zombie society is on the verge of a food crisis. Wataru, a zombie whose quirk is that he has retained his human intelligence and emotions, hatches a plan to achieve a breakthrough in the food crisis. His ambitious plan is to find surviving human males and females, breed them, and begin farming humanity (food)! However, the first surviving woman he manages to locate is his ex-girlfriend, for whom he still harbors feelings even now!?

(Source: Shogakukan, translated)