Tomoka Kusunoki

Iku's former best friend from junior high school. She has a huge crush on Yori and even slept with him. However, he later rejects her and she discovers of his and Iku's love. She threatens to expose them as part of getting revenge on them, like blackmailing Yori and hiring classmates to attempt to rape Iku. But is unsuccessful, as Yori is more conniving and intelligent than she is.

(Source: Wikipedia)