10 years ago, Erica's mother died in a questionable accident.

She left a flash drive with a locked folder called X-note.

Unable to understand it's purpose,

she continued living her life as a normal junior highschool student.

However, Erica is hardly normal, for she possesses power beyond normal human.

Erica's quiet life was interfered by a sudden visit of a man named Yoongi.

He invited her to investigate a murder case and a mysterious disappearance, in the Seoul Institute.

A school deeply related to Erica's mother.

Tempted by the possibility of unlocking X-note and solving her mother's mysterious death, Erica decided to take his request.

But what awaited her was more than she could possibly imagine.