[Suzerain of Sheol]

It's probably not actually that long, maybe a half-hour or so. It just feels like a huge chunk of game-time because of how short the game is at the moment.

And... I forgot about the two bosses in the flashback. The first one is pretty easy, the second one... well, there's a save point right before him. :p Remember to buff, though, and you should be fine, seeing as you have an end-game party for that part. ;)