One Piece: Mahoraga of the Beasts Pirates, Luo

[Beasts Pirates faction + some farming + multiple heroines + kill Momonosuke + not invincible]

Jeno was supposed to transmigrate into the world of Jujutsu Kaisen, but accidentally ended up in the world of One Piece instead. As compensation, the System gave him the Human-Human Fruit, Mythical Zoan: Model Mahoraga.

Jeno: “With this invincible power, shouldn’t I be able to become the King of the World in no time?”

System: “Keep dreaming.”

Jeno: “...”

Kaido: “Wororororo! Kid, what was it you said you wanted to become?”

Jeno: “Where did you come from?”