Warning: The following guide contains spoilers for Tekken 7's Story Mode, "The Mishima Saga."
It looked like Tekken 7's Story Mode ended with Kazuya finally prevailing over Heihachi and throwing his dead body into a living volcano. And while the epilogue looked to set up Tekken's future, the action from the volcano isn't entirely over. After completing the main story mode, you'll unlock one more "Special Chapter" that you can bring up from the Story Mode menu at any time.
So what's in this Special Chapter?
The Special Chapter returns players to the volcano, the site of the story's final battle. While Kazuya basks in his triumph, he's forgotten one last lingering threat: Street Fighter's Akuma. Akuma was last seen in the G Corporation skyscraper explosion, where he was seemingly gone and forgotten. But Akuma is ready for one last fight and if you thought the Chapter 14 fight against Kazuya was tough, then buckle up.
What to watch for against Akuma
Akuma has several moves that he'll spam without hesitation. He will use his Ashura Senku teleport often, using it to keep himself at a safe distance and also to cross you up. Pay attention to where he is and be sure to block any incoming combos. You will rarely catch Akuma off-guard off the Ashura Senku, because he can cue up a Focus Attack at a moment's notice.
Akuma's Gou Hadouken will be powered-up during this fight. If you time it right, you can use Kazuya's Hell Lancer flying kick to leap over the fireball and land a good hit. Akuma will frequently shoot EX Hadoukens in threes, which can juggle you for major damage, so be careful. If you're at a safe distance, you can use Kazuya's Devil Blaster beam to inflict some damage while hovering over Akuma's fireballs.
Akuma will take much less damage in this fight and be less succeptible to combos, so whenever you can land them, make them count. If you're at a safe distance, use Devil Blaster, but only if you're far away. Akuma is very fast and will take advantage of the Devil Blaster's long startup time to close any short gaps and nail you.
Counterattacks are the name of the game here, especially if you're going toe-to-toe. Practice your blocks and be ready to counter with quick combos. Be careful, because Akuma will also block frequently and he can take back momentum at any time if he baits you with a Focus Attack.
Lastly, if you deplete Akuma's health bar, he'll come at you with the Raging Demon. At this point, your Rage Art should be ready and you must counter with it. Getting hit with Akuma's Raging Demon is an automatic loss, so be ready to hit the right shoulder button. A quick-time prompt will not appear, so just be ready.
Even at the lowest difficulty, you will have to earn every bit of this victory. Be patient and fight an efficient fight. When you finally win, enjoy the (very brief) ending.