An immense explosion occurs, and Heihachi is projected miles and miles away into a forest, staying in the verge of death. While this happens, Kazuya turns into Devil and flies away, leaving Heihachi to die alone. Knocked down and surrounded, Heihachi is covered by an insane amount of Jacks, which start a bomb countdown.

For a mere minute, Kazuya and Heihachi battle as father and son should, but then, Kazuya, feeling they were at disadvantage, grabs Heihachi and throws him right into the middle of all the Jacks. All of a sudden, the helicopters launch enormous steel balls, which happen to be Jacks. Several helicopters draw near, and with their noise, Heihachi and Kazuya wake up. In this new Tekken 5 cut scene, Kazuya and Heihachi are in Hon-Maru. But instead of killing Kazuya, Heihachi takes him to where Jin is, Hon-Maru. He then meets his father, Heihachi, and Heihachi wins. When the battle commences, Jin is ambushed and caught by the Tekken Forces, and Kazuya is declared winner of the battle. Then, in an attempt to draw Jin and Kazuya to a fight, Heihachi launches the King of Iron Fist Tournament 4. However, when he sent his Tekken Forces to retrieve what was left of Kazuya, the Force was destroyed by Kazuya himself, who had been revived by the G Corporation and was stronger than ever before. However, knowing that his grandson, Jin Kazama, had one, he searched for him, also learning that his son Kazuya (also possessing the Devil Gene, but he died 21 years ago) was stored inside the labs of the Mishima Zaibatsu's rival, G Corporation. As he hadn't the Devil Gene, the experiment fails.

In Tekken 4, Heihachi got some blood and tissue from Ogre to splice with his genome, making him immortal. One of the many scenarios in Tekken 5, and one of my favourite

Devil jin tekken 5 full power