After you beat Orochi, he tells your team they should stop fighting and let him destroy humanity before it destroys itself. In a rather naive line, your team brushes it off and says that he doesn't need to worry about them.
Orochi then sends everyone to some kind of dark dimension. Though this would seem like some sort of last-ditch effort to kill your team, he instead tells your team that he is returning to his sleep.
With that, he teleports your team back to the real world with a flash of light, and the game ends with a brief epilogue questioning whether Orochi was truly evil. It's pretty anticlimactic if you aren't playing for a specific ending.
The best of the specific endings you get when you play through the game as the the holders of the three sacred treasures: Iori, Chizuru, and Kyo. The ending and cutscenes you get for playing with them are drastically different and have very extended cutscenes. You'll just have to play for yourself to see what happens there.