MTL - I, Luffy, Awaken the Sun God on the Top - Chapter 7

Youth, is meant to be used to shed sweat under the sun!

Youth, is to continuously engage in battles, and secure the win! The endless journey on Heaven’s Road, an endless expedition, a testimony of a hot-blooded youth’s legend!

A dream every man harbors, with the ignition of the blood! Forever young, Undefeated God of War!

- Description from Novelupdates

As a kind of punishment, the wings of a demon king were cut, and he eventually lost all of his power. To get back his power, he made a deal with the angel. He will go to the realm of humans to find a special girl with a special skill who is meant to be her queen. If the woman got pregnant, all of his sins would be forgiven, and he will regain all his powers. But he didn’t think that knowing her would be an adventure for him as the king of demons in the human realm.

This legend tells the tale of the protagonist, Kuroki summoned to protect the demon king from the hero.

Kuroki, unbeknownst to him, suddenly came to another world. He was summoned by the demon king, Modes. The territory which the demon king overrules was in the midst of being destroyed because of the hero. He had no choice but to bow before Kuroki.

“Please save us, Savior Dono!”

Kuroki nodded, deciding to save the demon king due to an unexpected turn of event.

Born with the fate of a slaughterer, but all he wanted to do was help.