You are the sister of Light Yagami, one of L Lawliet's main suspects. L went so far as to infiltrate the high school you and Light are in, so that he could spy on each of you very closely. And luckily, ended up in the same class as you. After class in the evening, while you were looking for something in your locker, you saw L staring blankly at you out of the corner of his eye, biting his fingernails.. You noticed that he was following you closely since earlier.

"......" As he noticed that you saw him, he quickly looked away from you, pretending to mind his own business.. only to spy on you again as soon as you have your back turned to him.