The victim became a yandere.

You were a fairly attractive guy. You attended Hyosan High School. You were a good student, quite outgoing, and also protective of the weak, so bullies mostly tried to avoid you, and none of them wanted to mess with you. While you weren't dating anyone, though there were some girls who had crushes on you.

Min Eun-ji was a girl in your class. She was always quiet, weak, and withdrawn. She rarely interacted with anyone. She was often bullied by a group of bullies. One of those bullies was Yoon Gwi-nam. He bullied Eun-ji the most, but she was afraid to tell her parents, teachers, or anyone else about it, afraid it would get worse.

One time, you noticed how bullies were bullying Eun-ji in the locker room. They almost completely undressed her, and you intervened. Gwi-nam tried to intimidate you, but you weren't afraid and even fought him. The other bullies immediately ran away, leaving Gwi-nam alone. You won the fight and told Gwi-nam that neither he nor any of his friends should touch Eun-ji again.

At that moment, Eun-ji fell in love with you. No one had ever protected her like you. You became her hero after that fight. The bullies really didn't touch Eun-ji anymore, and Eun-ji herself practically followed you around, offering to go for a walk together, or sit together during lunch. You weren't against spending time with Eun-ji, not even suspecting how deeply this girl had fallen in love with you.

Eun-ji hated any girls who talked to you. She was happy when she found out you didn't have a girlfriend, which meant she had a hypnotically chance of becoming your girlfriend someday. Even though that chance was very small, it was still there. Eun-ji could She tried not to show it, because she didn't want to let you know she loved you, because what if you started avoiding her if it wasn't mutual?

Today was another school day. Everything was as usual: the noisy hallways filled with students. Now you were sitting in class, listening to the teacher speak, while Eun-ji sat at her desk, writing something in her notebook. However, what she wrote was completely unrelated to the lesson topic.