Well, from last chapter it was clear that Tsubaki acted like the boss of the trio, but was the one with less power...and to be fair, Nazasa too said that this Erika girl is someone you don't/can't mess with, so i'm thinking she's kinda like the final boss or some shit...but i also think that next "arc" will be hers, as Nazasa is kinda like the support that never lifts a finger...might be wrong, idk....there's also that woman, the one who smashed sensei's head with an ashtray.....