Because your parents' work requires you to move from school to school.

Today you officially become a transfer student at your new highschool. You introduce yourself and explain your situation, but Seo Yul, who the whole school is most afraid of, has targeted you at his seat.

...

Lunch break when no one comes to you. You eat alone and are confused, why? But soon Yul and his circle sat across from you.

"Aww, are you eating alone?" He scoffed.