One day, a man entered a temple that housed forty-eight statues possessed by demons and made a deal: in exchange for ultimate power, they could each take a piece of his soon-to-be born son. Soon after the child came into the world and the demons held up their end of the bargain; the man then left the crippled child in the river to die. Found by a kind doctor, the boy grew older with the help of prosthetic limbs and enhanced senses, but soon demons began to follow him, and the boy - who his new father named Hyakkimaru - left to find a way to complete himself. He searches for the forty-eight demons; each one he vanquishes returns a piece of his body. Alongside the child thief Dororo, Hyakkimaru travels from place to place, hoping to one day become whole.
Long ago the infamous Gol D. Roger was the strongest and most powerful pirate on the seas. As he was about to be executed he revealed that he hid all of his wealth, including the legendary treasure known as One Piece, on an island at the end of the Grand Line - a treacherous and truly unpredictable sea. Monkey D. Luffy is a spirited, energetic and somewhat dim-witted young man with a very big dream: to find One Piece and become the Pirate King! However Luffy is no ordinary boy, as when he was younger he ate one of the Devil's Fruits and gained its power to become a Rubber Man. Now in this grand age of pirates Luffy sets out to gather a crew and sail to the most dangerous sea in the world so that he can fulfill his dream... and maybe even his appetite!
Most of the chapters of Dororo end with our heroes being told to leave the village that they just saved from demons. When I noticed this I immediately thought of how Luffy's pirate crew in One Piece has to leave the island that they just saved from bad pirates at the end of every arc. And their both shounen action manga. If you like one you should read the other.