Who Are You?

Minatozaki Sana is the new girl in town who transferred at the prestigious Seokjin High with a mission. She needs to know what kind of tragedy happens to her biological sister and as she gets closer to the truth, she discovers that maybe one of the people closest to her could be the culprit. Would she be able to unravel the truth before they uncover her true identity? Or are they the one who are hiding something?