Devil Survivor 2 - ep13

The final showdown begins, although inside of a straight up fight it is more of a philosophical debate over what is the best course for humanity to take. It seems that Yamato believe that his path is the only way thing could have gone because he feels without his resolve they would have never have pass the trials that were place before humanity. However Hibiki doesn't contest this fact but what he disagrees with is his heartless, in how he feels nothing for the people that lost their lives for his cause. That he wants to lead to rest of humanity down the same lonely path that he has tread, but Hibiki believe that even after everything that Yamato has done he still has a heart because if he didn't think of him as a friend than his dead face clip would have never been sent to Yamato. Eventually Yamato does agree that they are friends that maybe things could have been different if he found Hibiki earlier in his live, but that doesn't change how things are now. That they only way to see who is right is to fight, and Yamato challenges Hibiki. That if he believe that he was ever his friend than he must fight him now.

That in the fight itself they prove to be evenly matched, but once their signature summon defeat one another does Yamato bring out his trump card. It seems that you can combine demon to create an even stronger one, this results in him summoning Satan. Although Hibiki is saved by jack frost which was Daichi strongest summon, which leads to Hibiki gaining ownership of every demon that his friends were able to summon. That with these demons combined with the fusion system that Yamato showed him, it allows for him to summon a demon to match Satan. That with this he defeats Yamato granting him the right to choose the direction that humanity is going to take. This results in Hibiki restoring the world to what it was before everything happened. That in the end only Yamato and Hibiki remember what happen in that one week. This results in Hibiki bearing the weight of what happen and how the world almost ended.