When Kazuya Mishima is 5 years old, his father Heihachi Mishima carries him to the top of a mountain and callously throws him off a cliff to test his son's strength, whether he is fit to lead the Mishima Zaibatsu, the family business, and to see if he will be able to climb back up the same cliff. Kazuya survives the initial fall but left a large scar on his chest which causes a demonic entity within him called the Devil Gene to activate, offering Kazuya the opportunity to gain immense strength and power. Driven by his thirst for revenge, he climbs up the mountainside. To further motivate Kazuya, Heihachi adopts the Chinese orphan Lee Chaolan and raises him as a rival to his true son.
Over the years, Kazuya travels around the world and competes in martial arts championships, becoming an undefeated champion, with the only blemish on his record being a draw against Paul Phoenix, an American martial artist who seeks to settle the score with him. 21 years later, Heihachi decides to test his son's strength and worth and announces the (King of) Iron Fist Tournament in which the two would meet in the finals. However, Heihachi is unexpectedly defeated by Kazuya, empowered by the strength given to him by the Devil Gene, in an intense father-son battle. In an act of revenge, Kazuya picks up his father's unconscious body and tosses him down the same cliff that he was thrown off as a child. Smiling to himself, Kazuya becomes the new owner of the Mishima Zaibatsu.
