NRAAAH!!! $#@! it!!

[SeeDRankLou]

Second, I have personally verified by doing a 0.2% event that you do need to beat Trema for the 100% in one game walkthrough. You'll have exactly 96.0% right after you go to do the least events on the Celsius and before you go down to the farplane and finish the game. You need to beat Trema, there are scenes before and after you beat him that are worth percentage.

Wrong. I got 100% way before I beat Trema.

All you need to do is to get to the 20th floor of the dungeon to get the last Crimson Sphere.

Mmmmm......ok.....except for no. It is not possible to get more than 96% before you go to the farplane abyss, the remainder of the story being worth 4%. Unless you did it in a New Game+, which would defeat the whole purpose of a 100% in One Game playthrough.

It's impossible to get 100% in one playthrough.

I haven't fought Trema yet OR found the last crimson sphere and I got 100%

No, it is quite possible. Many people have done it.