Minami is Tomoko's second year and third year classmate in high school.
From what little the readers have seen of Minami, she appears to be very popular, sociable, and rather rude. She has no qualms against openly laughing at and mocking other students.
Minami has shoulder-length hair that curls at the ends. She wears two triangular hair clips on either side of her head. Her eyes are angled like Yoshida's but Minami's irises are larger, giving her a softer and friendlier appearance. In contrast to her softer appearance, she is drawn with a fang.
The two girls do not interact much, if ever. Nonetheless, Minami seems to have heard of Tomoko's reputation as a awkward deviant and laughs at her. Tomoko responds in kind with her own hostility.
Mako and Minami are friends. They ended up being in the same group during the school trip. Between the two, Minami seems to be the one taking a more active role in the friendship as she is the one who asked Mako to be part of her group. She also takes notice of Yuri's absence and invites Mako to lunch in chapter 99. Minami judges Mako for being friends with Tomoko, the resident weirdo.
Yuri and Minami have not been shown interacting as of chapter 99, but there are hints of them not being friends. In chapter 69, Minami invited Mako into her group for the school trip but did not invite Yuri. In turn, Yuri tells Mako to leave Minami's group without hesitation. In Chapter 117, she laughs when Tomoko falls, causing Tomoko to mock her teeth, Yuri snickers at this. In chapter 124, Mako compares Yuri to Minami, which causes Yuri to punch Mako in the shoulder, suggesting that she doesn't like Minami very much.
Minami and Asuka seem to be on good terms and are most likely good friends or are becoming friends. Not much else is known about their relationship.