Kimi to Warui Koto ga Shitai manga, I Want to Do Bad Things with You 君と悪いことがしたい
Mamori Wataya is a tall but dark, plain, and shady high school girl. One day she meets Kanashi Fuji, who has a small, thin body and an evil-looking smile. A supporting character that no one can find and a villain that no one likes. This encounter turns their gray days blue.