Dungeon of Knowledge - Chapter 18: Fire in the Darkness

Protagonist travels between different anime worlds to right wrongs and uncover his reason for being along the way.

In the Sky Sword Continent there are thousands of sects and strong cultivators as common as trees. In order to prevent his older sister from being forcefully married off, Lu Xuan had no choice to but to unceasingly cultivate and enter a sect to ask for a favor. By chance, a sword-shaped crystal of mysterious origins entered into Lu Xuan’s body, containing countless top-class martial skills, powerful martial arts, and everything you could wish for! A martial legend starts here…

He holds a god-level sign-in system in his hand, punches the goose factory, and steps on the pig factory. Do you think there is no good game?
First feed you two mouthfuls of tainted milk powder, and then send you the legend of the dragon and the Hearthstone gold cartoon for free.
What? Still not satisfied? League of Kings out-of-print skin, give away!
Satisfied? Tch, this is just the beginning…

- Description from novelbuddy

There was once a hero.

Unique black hair. Excellent eyes. Contrary to his delicate features, he who had abnormal strength was called the Otherworldy Hero.

At the hero’s long adventure (up to the point where his wooden sword that had been kindly granted to him by the king was replaced by the holy sword blessed by the holy maiden) he saved the prince that had been kidnapped by the demon king, and so the kingdom was swept by worry.

The hero’s strength that could fell the demon king was deemed too dangerous to leave unrestrained.

One advisor spoke up. Why not marry him to royalty?

The king thought that was a viable option. Family, to an alien from another world would be the best of chains. There was one problem. The king was abundantly blessed with sons and had princes galore, but not a single daughter.

Ho, and it wasn’t like I could marry off two boys.

At a burst of inspiration the king slapped his knee.

That was it!

You just had to turn a prince into a princess!

And so the hero ended up in a position to be marrying a man.

This story, is a tale of the aforementioned otherworldly hero, and his bride, the former-prince-now-princess and their ridiculously hilarious marriage.