Eiichiro Oda has mentioned that the animal Luffy most resembles is a monkey.According to Oda, Luffy is represented by the color red and he smells of meat. Like many protagonists of Japanese manga, Luffy has a huge appetite, often eating to the point of becoming comically fat.
Luffy's dream is to become the "Pirate King". He is portrayed as the carefree and sometimes airheaded captain of the Straw Hat pirates and is the son of Monkey D. Dragon, brother of Portgas D. Ace, and the grandson of vice-admiral, Monkey D. Garp. His trademark Straw Hat (from which he gets his nickname "Straw Hat Luffy") was entrusted to him by the pirate captain "Red Haired" Shanks, who inspired him to become pirate, when he was still a child.
Luffy grew up in a town named Fushia Village. He accidentally ate the Gomu Gomu no Mi, a Devil Fruit, giving his body the durability and stretchability of rubber. According to series author Eiichiro Oda, Luffy can stretch any part of his body. While defending the Red Hair pirates' honor from a gang of mountain bandits, Luffy is kidnapped by their leader, Higuma. Higuma takes Luffy hostage and escapes to sea, throwing Luffy overboard when he is no longer of use to him. Luffy is then almost swallowed by a fearsome Sea King; one of a variety of mammoth sea monsters that inhabit the oceans of the One Piece world. But Shanks saves him from the creature, losing his arm in the process. This event only serves to steel Luffy's determination and when Shanks and crew leave the island, Luffy decides to set his sights on becoming the "King of Pirates". When he told Rayleigh this and was told he would have to conquer the new world he said he didn't want to conquer anything but he thinks the Pirate King is the guy with the most freedom in the world.
Powers and Abilities
Luffy gained stretching powers from eating the Gomu Gomu no Mi at the cost of never being able to swim again, like all of the Devil Fruit people in One Piece. As a result, Luffy's body gained the properties of rubber, giving him stretching abilities. Luffy uses the malleability of his limbs to achieve tremendous velocity to strike enemies with devastating impact. His rubber body is virtually immune to recoil attacks. As such, blunt objects, punches and even bullets deflect off his body harmlessly. Fighters with superhuman strength however, such as CP9 member Rob Lucci, have proven capable of damaging Luffy regardless of his normal resistance. Luffy's body also resists electricity, an ability which gave him an advantage while fighting Eneru. Luffy is also able to store large amounts of liquids in his body (such as water) as seen during his battle with Crocodile.
Luffy's most powerful abilities are his upgraded Gears, which he developed after being beaten effortlessly by Admiral Aokiji. Luffy's Gears are used to enhance his basic attacks, and are regarded as different forms of his regular body. To date, Luffy has used two forms in the story; Gear Second and Gear Third. He has also been shown as capable of using both techniques simultaneously, although it greatly strains his body. Luffy has also demonstrated the innate ability to intimidate a foe into submission without throwing a single punch, much like his hero Red-haired Shanks, who did the same to the local sea monster at Luffy's village. This ability is known as "spirit" in the world of One Piece, and is exhibited by Shanks, Luffy and, more recently, Silvers Rayleigh.