MTL - Enter the Room - Chapter 294

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

Second Awakening? A System? Having lost the battle of the Dark Catastrophe to the demons—spawns of the Dark Gods— humanity is given a chance at making things right once again. Born as a twin into a family of high ranking talent awakeners, Damien Terrace is met with trouble when it is his turn to perform the ritual. After awakening the E-Rank Summoner talent, Damien loses everything to his twin. Exiled by his father to perish away from them, Damien goes through a second awakening that changes the play field for him. Ding! [The God of Summons is furious and has blessed you with a system!] [You have fused with the Mythics Summoning System—A system that only allows you to summon mythical beasts!] [Obtain nineteen Magic Essence Cores to boost your core to the next level!] [Slay 200 more demons to unlock another summon!] Damien’s only option is to evolve!

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