Monkey D. Luffy, also known as "Straw Hat" Luffy, is the main protagonist from the One Piece game series. He is a young adventurous pirate and founding pirate captain of his own self-founded pirate crew, the Straw Hat Pirates, named after his signature hat. At age seven, he admires and tries to join the pirates who were following of his idol and famous pirate, the "Red Haired" Shanks. Shanks rescued him from drowning, but he lost his left arm in the process. After this, Luffy gives up on joining Shanks, resolving instead to start a crew of his own and become King of the Pirates.
Wearing Shanks' straw hat ever since, Luffy eventually leaves his home and began forming a Pirate Crew of his own. Together with his treasured comrades, Luffy has experienced several adventures, gained precious friends, and has created an infamous reputation for himself. After the Battle of Marineford, he apprenticed and trained for 2 years under Silvers Rayleigh and learned how to use the 3 types of Haki at will.
At age seven, he inadvertently eats their treasure by accident, a Paramecia-type Devil Fruit: the Gum-Gum Fruit, which magically gives his body the properties of rubber and gained his signature rubber powers, as well as lost the ability to swim (not that he knew how in the first place).
Aspiring since childhood to live as a pirate, Luffy began his life at sea by following his idol and famous pirate, Shanks. Ridiculed and rejected, he inadvertently eats the Gum-Gum Fruit; which was their treasure. His reckless efforts ultimately lead him into grave peril causing Shanks to lose an arm while rescuing him. The incident cut his time with Shanks short.
Before their parting, Luffy proclaimed that he would someday become the almighty Pirate King -a pirate who possesses the legendary treasure "One Piece"- to surpass Shanks. Impressed by Luffy's bold claim, Shanks gave him his straw hat as a memento, and asked him to return it to him after he becomes a great pirate.
Displeased by Shanks spoiling his grandson, Garp takes Luffy to be raised by Curly Dadan and her mountain bandits, who he strong-arms into taking him in. During Luffy's time there, he becomes a sworn brother with Garp's other ward Ace, and local runaway noble Sabo. Ten years later, and still wearing Shanks' treasured head covering, Luffy forms and captains his own pirate crew called The Straw Hat Pirates and sets sail for the Grand Line, quickly gaining infamy.
Eventually, after his strength proves insufficient to save Ace from execution, he spends two years on a secluded island, before entering in the New World, learning the use of the three color forms of Haki as well as Gear Fourth from Silvers Rayleigh, before heading to the New World.