Katsuragi Keima is the biggest seducer on the net, to the point of being dubbed the God of conquests. In real life, however, he's a boy who's denigrated and rejected by his classmates. This has led him to hate the girls he associates with.

But one day, a female demon, Elsy, whose mission is to capture the souls that have escaped from hell, teams up with Keima.
These souls take refuge in women's bodies, and the only way they can get out is for the girl in question to fall in love with Keima.

Chained to Elsy by a deadly necklace, Keima now has his title of God of Conquests put to the test as he is forced to navigate his way into the hearts of a multitude of real-life girls.

But this is no mean feat, as the gap between theory and practice is immense.