One Piece

The series begins with the execution of Gol D. Roger, a man known as the King of the Pirates. Before his death, he told the legend of his treasure, the One Piece. Roger's death caused a Great Pirate Era (大海賊時代, Dai Kaizoku Jidai^?) as countless pirates set out to look for his treasure.
Twenty years have passed since Roger's execution, and Monkey D. Luffy, a young boy inspired by the pirate known as "Red-Haired" Shanks, sets off on a journey from the East Blue to succeed Roger and find the treasure. Along the way, he organizes and leads a crew named the Straw Hat Pirates. The crew consists of a swordsman named Roronoa Zoro; the navigator and thief Nami; the liar and cowardly sharpshooter Usopp; the womanizing chef Sanji; the doctor Tony Tony Chopper, an anthropomorphized deer; the archaeologist Nico Robin, a former villain; the cybernetic shipwright Franky; and a musician skeleton named Brook.
The crew crosses paths with diverse villains, such as the Seven Warlords of the Sea and the Marines, who place bounties on Luffy and Zoro's heads. They encounter Baroque Works, the crime syndicate responsible for a civil war in Alabasta, and meets Blackbeard, whose dream is also to become the King of the Pirates. The crew also encounters Eneru, a ruler of Skypiea. Later, the crew meets Aokiji, who reveals that Robin was involved in searching for Poneglyphs, stones with markings left by an ancient civilization whom Roger himself was also able to read. The crew also encounters Cipher Pol No. 9, the intelligence agency responsible for the destruction of Robin's homeland, whose actions cause them to declare war on the World Government. After an epic battle at Enies Lobby, the crew defeats CP9, avenging the lives of people lost in the destruction, and receive bounties on their heads.
Later, the crew completes their journey to the first half of the Grand Line. After a battle at the Sabaody Archipelago, the crew gets separated. During this time, the Marines sentence Luffy's older brother and Roger's son Portgas D. Ace to be executed, and they hold a war against a group of pirates led by Whitebeard. Luffy eventually rescues Ace, but both Whitebeard and Ace are killed in the ensuing chaos. Later, Luffy and the crew undergo rigorous training regimens, some under the tutelage of prominent figures. Two years later, the crew regroups and set out on a journey to the New World, the second half of the Grand Line. They travel to Fishman Island; however, they are drawn into a coup d'etat staged by a group of fishmen pirates led by Hodi Jones.

Wikipedia