Saaya Agata
Saaya Agata is the tsundere girl from class 2-B. She approches Sket-Dan with the request to help her become less “tsun”. She is Soujirou’s little sister.
Eventually she starts to hang out with the group, and would sometimes help out too.
In episode 64 she admit that she has a crush on bossun since he accepts her and cares about her. And she note that she can’t stop thinking of him.