The Strongest Guild Master Founded a Nation in a Week - Chapter 154 - Elves and Beastkins, To G.I.Jou

Upon meeting the girl who would become her adopted younger sister, the duke’s daughter Christina regained memories of her previous life. Through those memories, she learned that her new sister, Mishuli, was the heroine of a certain story. And though the story depicted a Christina who abused her sister, the real Christina turned into a siscon who spoiled Mishuli to no end.

The Saint: “Bro Yi, Can you make me your servant?

Yi Feng: “What? A Saint like you wants to become my servant. Do you have any shame?

The Saint: “My sister is very beautiful”

Yi Feng (His eyes is glowing): Little Saint, you can follow me from now. All right, remember to tell your sister to come!

The King: “Yi Feng! Your bastard, what are you doing?

Yi Feng: My bad! My bad! My king, I just want to stroll in this harem a little bit. Who knows those girls have been following me like that?

- Description from Novelupdates

A novel revolving around being transported to another world with an op system. The mc spends his day chasing skirts and doing missions to level up. A standard journey to the top with lots of girls from various animes and games with a twist of that gaming feel (hunting mobs, doing missions).

- Description from novelupdates

In the rebirth, in order to prevent the tragedy of the previous life from happening, Bai Yu decided to rush to the [Tower of God] at any cost, and face everything together with his sister!

However, Bai Yu, who was bound by the system, mutated his bloodline, and transformed into a black-scaled python seems to be developing on a completely different path from his previous life…

- Description from novelbuddy