High School DxD - Volume 2 Chapter 5

In the whole world there lays twelve paths to climb the Tower of God, and in legends these twelve pathways leads toward legendary road of immortality. However these paths in the Tower of God, are far too long, without end.

Worlds overlapped, and Alien Species descended.Strange entities emerged one after another, as the shadow of evil spread wildly.The calm of life was shattered, and Zhang Xiaoman, inside a fish's stomach, accidentally consumed a system named “World-saving Plan”.From then on, he became the only person among all humans with Extraordinary Power.…Inventing an ancient oath, he established a unique methodology, Cultivated Dark Energy, founded an organization, took Control of the Transcendent, and resisted invasions.Well, this is actually the story of how a Big Con Man bluffed his way into saving the entire world.PS: Contains elements of the behind-the-scenes, Cthulhu mythos.

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.

In the year Stardate 1, mankind entered the interstellar age, with interstellar migration, spaceships, alien races, and outer gods...arriving one after another.By the year Stardate 717, Fang Xing looked out upon the cosmic backdrop teeming with dense armies of foreign races and declared that all aliens, cultivators, tentacles, esoteric teachings, and evil gods would be intimidated by his supreme talent and smashed to pieces with his iron fist...Well, this is actually the story of a transmigrator, who whimsically dominates many different worlds with the help of his professional panel...