Yuzuko Kasai

Yuzuko was a recently transferred student when Reiji was still in elementary school. His class was told by Arisu (one of the students) to ignore her because she's "too full of herself" but Reiji said he wouldn't which caused him to be ignored by the rest of the class after Arisu told them to. Afterwards, she became friends with Arisu and they both meet Reiji again in chapter 23 though he doesn't remember them before they tell him who they were.