Kazuya as seen in his T4 epilogue regained all of Devil's power once again. At the start of T4 he only had half of said power and Jin possessed the other half. Kazuya's power caliber in his T4 epilogue is the same amount of power he had in T2, possessing all of Devil's power at once.YouTube videoAs you just read at the last part of the video, Devil at full power wiped out the entire Mishima Zaibatsu compound as well as the area surrounding it to the point that it vanished completely. That place is the whole area seen in the T5 intro where many helicopters were watching the Honmaru scene. It is also the area shown in Kuma's T5 prologue:YouTube videoOn that same day Kazuya wiped out the complex, and even when Kazuya fought Heihachi in the arena it was during the night. All of the events that occurred after that took considerable amounts of time, and Kazuya managed to wipe out the Mishima Zaibatsu and the area surrounding it within that same day.
This is unlike Akuma managing to either sink his island or crumbling it by channeling just about all of his energy into his hand, as I've read in every source describing the attack he used.
Raging Demon? Sure it wasn't the Kongou Kokuretsuzan? I knew he used energy to fight Ryu. What I meant was he used the remaining energy he had to destroy his island. Would be smart to say that he didn't use a lot of his energy against someone like Ryu.
Edit: *cough* Ryu didn't equal Akuma using the Dark Hadou just so you know, and normal Akuma equaling Ryu makes Akuma...as powerful as Ryu. 😂