Fifteen years after the King of the Iron Fist Tournament 2, Heihachi Mishima has established the Tekken Force: a paramilitary organization dedicated to the protection of the Mishima Zaibatsu. A squadron of the Tekken Force searches an ancient temple located in Mexico under the premise of an excavation project. Soon after arriving there, Heihachi learns that they have been obliterated by a mysterious yet malevolent creature who is known simply as Ogre. Heihachi, having captured a brief glimpse of Ogre with his own two eyes before its immediate disappearance now seeks to capture Ogre in the hopes of harnessing its immense fighting power for his own personal gain. Soon after, various martial artists end up dead, attacked or missing from all over the world, with Ogre behind it.
Jun Kazama has been living a quiet life in Yakushima with her young son, Jin, fathered after the events of the previous tournament by Heihachi's son, Kazuya. However, their peaceful life is disrupted when Jun begins to feel the encroaching presence of Ogre. Jun is now a target and instructs Jin to seek Heihachi should anything happen. Sometime after Jin's fifteenth birthday, Ogre indeed attacks. Against Jun's wishes, Jin valiantly tries to fight Ogre off, but Ogre knocks him unconscious. When Jin awakens, he finds that his house has been burned to the ground, and that his mother is missing and most likely dead. Driven by revenge, Jin is confronted by the Devil, which brands Jin's left arm and possesses him. Jin goes to Heihachi, explaining his situation and identity and begging him for training to become strong enough to face Ogre. Heihachi accepts and takes Jin in, as well as sending him to school to where Jin befriends a fellow classmate named Ling Xiaoyu and her pet Panda.
Four years later, Jin masters the Mishima karate style. On Jin's nineteenth birthday, Heihachi announces the King of the Iron Fist Tournament 3, secretly intending to lure out Ogre, while Jin himself prepares for his upcoming battle, having no clue or idea that his grandfather is secretly using him, Xiaoyu (who had entered the tournament in the hopes of winning the prize money so that she can use it to build her own personal amusement park), and the rest of the competitors as bait in order to lure Ogre out into the open.
In the tournament, at a large temple, Paul Phoenix defeats Ogre and walks away from the tournament, thinking he is victorious. However, Ogre transforms into its true form of a monstrous beast, and Jin finally confronts it. Jin battles and defeats Ogre, and the being completely dissolves. However, Jin is suddenly gunned down by a squadron of Tekken Forces led by Heihachi, who, no longer needing him, personally fires a final shot into his grandson's head.
However, Jin, revived by the Devil within him, reawakens and dispatches the soldiers, smashing Heihachi through the wall of the temple. Jin catches Heihachi right before he hits the ground, and he looks up to see Jin sprout feathery wings and fly off into the night.