Season 1

Is it the low marks from the tutoring center bothering Ji Yu? Or is it the cold shoulders at school? Ji Yu feels so small and tries to find peace through her boyfriend. Ji Yu fails to find friends after the semester begins, but A Ra, the transferring student, approaches Ji Yu. Meanwhile, Ji Yu starts have doubts about Chan Seong - her entire world.

As Ji Yu is in agony, the person who understands her is San, who is always by her side. Meanwhile, due to an incident with Do Ha, an older student, Ji Yu experiences an unexpected event. Ji Yu feels better as Chan Seong is sweet to her but not completely. Then Do Ha comes to Ji Yu.

Ji Yu starts spending time with her new friends. During this time, Ji Yu's relationship with Chan Seong gradually suffers. At the same time, the two suppress their frustrations over unresolved issues. Meanwhile, Ji Yu meets up with Do Ha, who keeps advancing to her, and San finds out, even though it was supposed to be a secret.

After talking to San, Ji-yu wants to be honest with Chan-seong, but it doesn't go her way; the more she tries to explain, the more Chan-seong misunderstands; in the end, Ji-yu is fed up and the two turn their backs against each other.

Ji-yu meets with Chan-seong to have a talk and clear up a misunderstanding; she experiences an unexpected conflict with Mi-na later on; Ji-yu, who becomes the subject of a rumor once again, tries to resolve the situation.

After clearing things up with Mi-na, Ji-yu and her friends pay a visit to the gynecologist. Meanwhile, to make things right, Ji-yu goes to find Do-ha to rectify things. Chan-sung goes to meet Ji-yu after hearing about the rumors, but an uninvited guest shows up and things turn ugly. As the situation worsens, Ji-yu hears surprising news from San.

Ji-yu is confused about Mi-na and San getting along so well. Then, Ji-yu gets hate DMs from an anonymous Instagram account. Instead of running away, Ji-yu makes up her mind to face reality. Taking courage, Ji-yu meets up with Chan-sung who has been avoiding her to have they heart-to-heart talk they couldn't have and share a genuine conversation.

Ji-yu decides to make decisions only for herself and decides to break up with Chan-sung. Then Ji-yu apologizes to Su-jin, who she must have been hurting all along. Meanwhile, sports day is coming up at Jungang High. Looking for San, Ji-yu goes to the nurse's office and sees something shocking.