Extra's Harem: Invincibility Starts with Marriage and lots of Children - Chapter 154 - Laugh while you kill

…but it seems pretty doable.

Lucifer travels to the world of One Piece, binds the system, and obtains the fruit of words and the power of hell demons at the beginning.Everything Lucifer says will become reality, and matter can be summoned or generated through sound.Flash, lightning, fire, ice, magma, gravity, earthquake, all powerful abilities, Lucifer can use.By beheading enemies, Lucifer earns kill points, which buy more powerful powers.Akainu: As soon as Lucifer speaks, my magma can only be used to light candles.Kizaru: As soon as Lucifer opened his mouth, my flash was slower than a turtle.Whitebeard: My Shock Fruit can't shake a rock.Kaido: My immortality has failed.Redhead: Why is my strongest Conqueror's Haki gone?Five Elders: Please, stop talking.Lucifer: I haven't done it yet, why are you so stupid?Everyone: You didn't do anything, but you did.Lucifer: A gentleman uses his mouth but not his hands.From then on, a hell demon who used his mouth to attack invincible opponents all over the world was born.Disclaimer: This is Translation

[*Ding*

Akira, was born in the slum and wishes to get out but the only way he could was to risk his life in these ruins as a hunter.