Here's my schizo rrat analysis on why this is a clique: Gura, Mumei, and Fauna roommates are all hot white girls. Kronii has charisma and is naturally funny so she's in but as the token minority friend that would let them copy her homework because she's asian. Also reportedly a fashionista so she would fit in. Everyone else is too different, Ame, Calli, Sana, and Ina are hard nerd-coded and would sit at the weird kid table, Kiara is too culturally different and blunt being a euro, Irys didn't debut in a gen so she was hit up by Calli first who lives in Japan like her, and Bae is an aussie and confirmed by the others to be the most attractive so they're intimidated by her.
High school antics are metaphysical and lasts forever is basically what I'm saying.