One Piece: Becoming an Admiral with the Float-Float Fruit

When he was young, Ryan Hart's Marine parents were brutally murdered, and he himself was enslaved aboard a pirate ship for years.

At last, when he was ten, he was tortured to death.

At the same time, a soul that had transmigrated from Earth merged with his body, awakening a cultivation System: train once a day to gain one unit of strength, complete missions, and claim rewards.

In the end, he destroys the pirate ship, carries on his parents' legacy by joining the Marines, and earns the title of Celestial Dragon Admiral after obtaining the Golden Lion's Float-Float Fruit through the System.