Lee Ah-jin

A class of students stays at school for a camp in an elite study group to finesse theirs and the school's grades. Upon the first night, the swimming coach is found murdered. As the students try to figure out what happens, a voice informs them that if they don't figure the murder out, students will begin dying in quick succession.

Sixteen-year-old Yeo Lin used to have a boyfriend and normal life, but everything changed when she lost both her parents two years ago. To support her siblings, she sells her body. Quietly bearing wounds and responsibilities beyond her age, she faces the cruel trials of love, friendship, and premature adulthood, and she does it all in seeming detachment. Always tired, Yeo Lin suffers from chronic insomnia and relies on medication to sleep. For Yeo Lin, sleep is an escape that she wakes from too soon.