Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.
I'm not entirely sure specifically what 'u of u invetro' refers to. It could be something very specific to a particular institution or field. Maybe it's about the University of Utah (assuming 'u of u' means that) and some in - vitro related research or experiences there. Without more context, it's hard to say exactly.