What's the worse thing that can happen to a hero? Getting killed by the demon lord, watching the world gets destroyed right before your eyes or suddenly being proclaimed the wife of the demon lord.

Marcel, the hero since childhood had always wanted to be like the proud, gallant and valiant heroes who came before him, although they all didn't return. The demon lord has remained undefeated for as long as anyone can remember since well, the demon lord does nothing to threaten the balance of anything. All he does is boss around the nobles who offend the people, sometimes destroying them and dealing with the heroes sent after him. You could say he's the epitome of not the demon lord, more like the best hero ever with the exception of eliminating the real heroes. He makes all his demon subjects have a comfortable and carefree life, not worrying about the human world. The demon realm flourishes in abundance with happiness and prosperity.

A prophecy arrives from the demon lord's trusted adviser, the seer who mentions that the demon king will be defeated by the next hero who comes to the demon realm. He panics for weeks and then he had an idea, what if he just made the hero his loyal wife, then he won't have to worry about getting defeated. He hastily tells the spirit of the world his plans and the spirit of the world hastily grants Marcel, who was ten years old the title of Hero and Demon Lord's wife. Now, who will be defeated in the end? The headstrong hero or the moral Jesus that is the demon lord.

Warning: NSFW content. You've been warned.