[Ultear's Crystal] Highest Rank

[Madtanner]

I'm at +10, how high does it go?

[A-tanatos-Ω]

99? 999? Who knows? But if you have so much free time to burn, try and tell us )

[Kapika96]

Is there even any point in going that high? Your characters should be maxed out way before +10.

[Blu Ray]

You max out stats at around 3 even at level 1. You could just use cheat engine to keep upgrading to see if there's a limit but I don't think there is.

[The Yellow Flash]

Max value is +99 but you can still reset your level at that point.
It just wont increase the value any more at that point.