High school student Ra Eun Ho dreams of going to college with her older crush, but her grades are a major hindrance. Classmate Hyun Tae Woon fails to impress his father, while top student Song Dae Hwi is more than meets the eye.

Eun Ho is caught in the wrong place at the wrong time. Mr. Shim tries to help clear her name.

The principle offers merit points to anyone who reports the identity of X. Eun Ho learns of a contest that could potentially guarantee her acceptance to Hanguk University.

Tae Woon's continued masquerades as X force the principal to play a stronger hand. Eun Ho and Sa Rang face stormy weathers in their friendship.

Eun Ho, Tae Woon, and Dae Hwi accept an unofficial punishment for their actions. Mr. Shim takes a new approach to stop the tattling.

X reveals his identity to Eun Ho. Dae Hwi feels stressed, realizing his accomplishments may not be good enough for his goals.

Tae Woon takes the fall for the math competition fiasco, but manages to bring the principal down with him. Meanwhile, tensions rise and the school is at risk for an official investigation.

Tae Woon and Eun Ho try to protect Dae Hwi. Nam Joo feels insecure about her relationship and her own secrets.

Tae Woon tries to fix things with Eun Ho. With new standing, the principal makes his move on catching X once and for all.

Eun Ho and Tae Woon become a couple. Meanwhile, a new problem with the school arises, and once again the student body suffers.

The chairman plots to drastically resolve the X issue, and while both Tae Woon's and Eun Ho's futures are threatened, Eun Ho decides to take the matter into her own hands.

As the dynamic of their relationship shifts, Eun Ho and Tae Woon become awkward around each other. Rumors fly about Bo Ra and Hee Chan.

The school administration has a shakeup after the the school violence hearing ends. Tae Woon and Dae Hwi are forced to resolve their mutual agitation.

The whole school is shaken at how Eun Ho's hearing turns out, and though Tae Woon is prepared to take the fall, not even X can fix it all this time.

Eun Ho feels conflicted after running into Dae Hwi. Mr. Shim is pressured to break the rules.

Tae Woon inspires Eun Ho to bring out her fiery side. Hee Chan looks into a possible connection between Eun Ho and X.