18+ Megami to Ichinen Kurashitemita.

In order to rise to godhood, goddess-in-training Chisa must live in the human world as a guardian goddess to a human for one year. And she chooses... Keigo, a loser who only thinks about sex. But Chisa doesn't know anything about the human world, and it's up to Keigo to teach her. Together, they're about to give in to their basest desires.

(Source: Lezhin Comics)