Negai wo Kanaete Moraou to Akuma wo Shoukan Shita kedo, Kawakatta node Kekkon Shimashita: Akuma no Niizuma (Light Novel)

The young orphaned adventurer, Theo Asper tried summoning the devil to help his career as his own skills are lacking. The devil comes in the form of a beauty who offers to grant him one wish. He’s so enamored with her appearance that he just falls in love at first sight. He says the first thing that comes to mind, to become his wife. She blushingly agrees to his surprising demand and they go on to future adventures together.