My Wife and I Became Sages in Another World - Chapter 446: The Primordial Demon, Agares

Another entry in what you can call the Proto Harem Series: the books written before the Harem Series that take place in the same world.

It’s about a swordswoman whose student is captured, so she goes to rescue her.

Xiao Ran transmigrated to a fantasy world. As a dungeon guard in the Celestial Dungeon, with a special floor called the Purgatory meant for powerful demons and martial arts experts, he faced a huge challenge from the start. The Eldest Princess acquired a forbidden martial arts technique and was banished to the Purgatory. However, no one was powerful enough to restrain her. All the dungeon guards were defeated. Xiao Ran stepped up and declared, “Your Highness, it’s better for you to behave yourself on my territory” and effortlessly subdued the Eldest Princess.

He progressed from imprisoning the Eldest Princess to delivering the Great Xia Kingdom from the evil clutches of various demons and evil martial arts experts.

…

Xiao Ran was the mastermind behind the scenes.

Xin Yun, a sarcastic young man, traveled to an unknown world by chance, but lost his chance to become the strongest because of his obsession with women... or sex. In a collision of the powers of nine powerful men, an incredible thing happened. Xin Yun was reborn back to the time when he traveled to the Isekai world. A fantasy journey is about to begin... [The comic adapted from this novel is popular all over the world]