I quit the Straw Hats at the beginning and joined the Beast Group

Time travel to pirates.

In the beginning, at the invitation of Pirate King Luffy, Ren joined the Straw Hat Pirates.

But because he learned lessons along the way and kept finishing up on enemies with low health, he got into disputes with other members of the Straw Hats who were too much.

In anger, he quit the Straw Hat Pirates.

As a half-blood of the Lunarian tribe, he also gained the ability to take the form of the Cow-Niu Fruit, the Phantasmal Beast Species, and the Kirin Form.

So he turned around and joined the Beast Pirates, and became Kaido's son-in-law and Yamato's fiancé.

Before the war, he coldly refused Straw Hat Luffy's request for help.

"Sorry, I don't want to play house with you anymore!"

"From now on, please call me the fourth natural disaster of the Beast Pirates - Blood Prison Renn!"