Shizuru Kanzaki

A teacher at Eisei High School in her early twenties. Kanzaki is the homeroom teacher in Kisumi's class, as well as the tea ceremony club's advisor. She is a Japanese-style beauty with a calm and polite tone, but she is rather dry and reckless in her statements. Her demeanor is always elegant, her back is straight, and her movements are without a hint of stiffness. Despite her young age and relatively little teaching experience compared to other Eisei High School teachers, she has earned the trust of the senior teaching staff with her responsible approach to teaching students.

As the former homeroom teacher of Yoruka's big sister, Arisaka Aria, with whom she keeps in touch even after her graduation, she wants to help her make friends with the class and transform. However, due to the fact that Arisaka shows one-sided hostility towards her, mistaking her for her "natural enemy", Kanzaki had to take Arisaka in a roundabout way: she personally asked Kisumi to get closer to Arisaka and make her friends with the class.
Her method leads to a fruitful result, as a result of which Arisaka started dating Kisumi, makes friends, and no longer rejects others with such hostility, however, Arisaka still reacts sharply to the moments when Kisumi is left alone with Kanzaki, jealous.

It is later revealed that the reason Arisaka is so wary of Kanzaki is because she changed her big sister during her high school years. Yoruka's older sister, Aria, seeing Yoruka trying desperately to imitate her, was worried for her that she would beat herself up this way. Aria didn't know what to do with her, so she turned to Kanzaki for advice. Kanzaki advised her to change in such a way that Arisaka would become disillusioned with her and start looking for her own path. In the end, this plan worked, but only partially: Arisaka stopped chasing Aria, but got stuck in place and did not know where to go next, as a result of which, her hatred was directed towards Kanzaki.