Well, I have the guide to it, but-I don't know. There are some typo's-but, it says that the common ending occurs in all of them, I think. If you don't have 100% completion, then you'll just see the common ending. The good ending is when you take down Vegnagun piece by piece, but if you don't have one 100% you won't see the perfect ending.

And finally, the perfect ending-take down Vegnagun, not just the leg or the game will end auto, the faith ask if you want to see someone-say yes, and there you go.