Y'shtola is a Mary Sue.

[Shironeko_Narunyan]

In the same vein, Y'shtola is a one-note character. She only seeks the pursuit of knowledge and that's it. She never wavers or shows vulnerability no matter the circumstances.

Seriously, stop using words you don't understand. At least make an attempt to learn the definitions first. There's a difference between over the top stache twirling "buhahaha fightfightBLOOD" and a character like Y'shtola, who you see react differently in various situations.

If you want to break down any character to their most dominant trait, be my guest. But please don't then do it using established vocabulary in a wrong way.

"One note" does not mean what you think it does.