One Piece: Supreme Check-In System - Chapter 12: Jessie’s Conqueror’s Haki: Deterrent of Kings

Crossing to One Piece world, he became Roger’s younger brother.

Liu Duo was a young girl whose grandmother sold her to four brothers with the intent to be a bride. Unwilling, she ran away the following night, only to fall unconscious while trying to get away. Unexpectedly, however, she was reborn with the spirit of a 25 year old woman, also named Liu Duo.

- Description from Novelupdates

Emperor Zi Yu used 5 strikes of his axe to split mountains and unify everyone underneath the heavens. He partitioned the land into 9 areas, thus establishing the Nine Cauldrons which eventually became known as the 9 prefectures.

In the year 2025, humans awakened with the ability to summon mighty beasts—capable of destroying terrains, breaking the laws of physics, and creating wonders limited only by one's imagination.But before these blessings came a curse.An alien face appeared from nowhere and threatened all life on the planet, leading to the greatest war in human history.In the aftermath, the human race and the alien race were forced into a shaky treaty that could be broken at any time.Years later, tests for summoning abilities began for the next generation. Those who awakened low-grade summoning would be thrown to the gutters, while those who awakened higher got to join great factions after graduating from the academy.Kairos Veyl, the blank, calculating student, pulled his hand from the massive crystal pillar and stared at the large beast before him.“This kid—he just got a LEGENDARY SUMMON.”A legendary summon? The greatest class of summoning. However, with this class came a risk one would have never guessed.