<P> Eventually, Luffy develops his latent ability to use Haki (覇気, ambition). This ability has two main types: Armament Haki (武装 色 の 覇気, Busōshoku no Haki), an armor - like force which can amplify defense and the force of attacks and negate a Devil Fruit user's defense, allow physical contact and damage, and Observation Haki (見聞 色 の 覇気, Kenbunshoku no Haki), a sixth sense which can read a person's moves and detect their presence . He also has a rare third type, the Conquering King's Haki (覇王 色 の 覇気, Haōshoku no Haki), which can render people or animals near him unconscious . Two years later, Luffy masters the three types of Haki and uses them with his improved attacks . As a result of his encounter with Magellan, he has also developed an immunity to poison (although it is implied that a strong poison may affect him). During his fight against Charlotte Katakuri, Luffy's Observation Haki gains the ability of seeing several seconds into the future . </P> <P> Luffy develops another technique, Fourth Gear (ギア 4 (フォース), Gia Fōsu) (similar to Third Gear), inflating his muscles to increase the size of his limbs (except for his legs). He can make destructive moves by compressing and releasing his limbs, and can fly in a similar fashion to CP9's Moon Walk (月 歩, Geppō) technique . </P> <P> Luffy first appears as a young boy in Windmill Village, who befriends the pirate "Red - Haired" Shanks and intends to become one himself . Before the series begins, he accidentally eats the Gum - Gum fruit and acquires rubber powers . Luffy is later saved by Shanks from being devoured by a Sea King, a large sea beast, and Shanks loses an arm . Ten years later, Luffy leaves the village in search of the One Piece treasure and to become King of the Pirates . He meets swordsman Roronoa Zoro, ocean navigator and thief Nami, cowardly marksman and liar Usopp, and chivalrous chef Sanji, and invites them to join his crew . Luffy also encounters and defeats the East Blue pirate Buggy the Clown and the fishman Arlong, becoming known to the general populace and the pirate - hating Marines . He later accepts an offer to return Princess Nefertari Vivi of Alabasta to her homeland to stop a rebellion incited by Seven Warlords of the Sea member and Baroque Works crime - syndicate leader Sir Crocodile . After he defeats Crocodile, Luffy accepts Crocodile subordinate Nico Robin as his ally . On Drum Island he finds reindeer doctor Tony Tony Chopper, who also joins his crew . </P> <P> While visiting Skypiea, the crew is drawn into a war . Luffy defeats the god Eneru, ending the war . He meets Admiral Aokiji, who easily defeats him . Luffy learns about Robin's background and faces enemies connected to her, such as Franky (a cyborg who becomes Luffy's ally) and the intelligence agency Cipher Pol No. 9 . Luffy and his crew save Robin at Enies Lobby . After their fight with CP9, Franky joins the crew . Luffy enters the Florian Triangle and encounters Brook, a skeletal musician . To return Brook's shadow, he defeats warlord Gecko Moria . After releasing the rest of the island's prisoners, Brook becomes a member of Luffy's crew . They go to the Sabaody Archipelago, and have Silvers Rayleigh coat the Thousand Sunny to enter the second half of the Grand Line . After Luffy's encounter with Admiral Kizaru and warlord Bartholomew Kuma, he and his crew are sent to separate parts of the world . </P>

How old is luffy at the beginning of one piece
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