Ore ga Akuma de, Aitsu ga Yome de.

Demons will grant any human one wish in exchange for their soul. Anzam Nia, an ambitious demon, has fallen to the bottom of the chart, having collected zero souls. After being kicked out to earth by the police, he found himself in Japan, in search of a human contractor in order to get back home. Then he crosses his way with a lonely little girl, who is convinced he is an angel sent from Heaven and insists that he grant her wish and form a contract with her, knowing it will take away her life? Anzamu Nia's first contract is formed, and her wish is... for them to get married?! So starts the blissful married life of this adorable and idiotic couple.
A marriage of different races, ages and personalities will now commence!