The good-for-nothing eldest son of the Xiao family, Xiao Fan, was beaten to death by his younger brother and sent to marry the ugly people of the Long family in exchange for training resources. However, he accidentally activated the most precious treasure in the world: the Zhoutian Star Map.

Every time a star is broken, various spiritual treasures, spiritual stones, elixirs, and techniques can be obtained.

Gu Changtian accidentally travels to the world of One Piece and is bound to the One-Punch Man Summoning System. In the One Piece world, he establishes the First Legion and continuously accumulates shock points.

Such a terrifying demon has crossed over into the world of One Piece. What will become of the One Piece world...?

"The Warring States period was terrifying; the First Legion members were all like monsters..."

Whitebeard: "Giants are the strongest men in the world..."

Redhead: "Oh no, my pride isn't working anymore..."

Garp: "Even my iron fist can't beat the First Legion..."

Kizaru: "No matter how much money you offer me, I won't fight the First Army..."