Boogiepop wa Warawanai: VS Imaginator

Taniguchi Masaki had just moved back to Japan, and found himself incredibly popular with the girls at his school, and equally hated by the boys. One day, he failed to notice a group of thugs moving in to attack him. A girl, Orihata Aya, stepped in to help Taniguchi, offering herself up in Masaki's place, but before things got out of hand, a man stepped in to save them. Because of this encounter, the two of them start to get closer, but...

(Source: Wikipedia, Crunchyroll)