School

Da In struggles to adapt to Dongkwang High School after transferring from an alternative school.

As part of efforts to become a model school, Gye Nam initiates the School Guardians Campaign.

Following unreasonable physical punishment against Se Chan, Seok Ju mobilizes the entire class to boycott.

Da In tries to help Yu Jin by being her friend. Meanwhile, a misunderstanding leads some girls to bully Da In.

Yu Jin is happy as other girls suddenly treat her as their friend. Da In becomes the "super outcast."

Da In discovers why the girls have been mean to her, and Won Seok realizes that he wronged Seok Ju.

Jun Hee's past is revealed, and upon recognizing her as his former tutee, Jae Hyun endeavors to help her.

Jun Hee tells Jae Hyun that she loves him. Jae Hyun, who had only thought of her as a student, feels confused.

With planning the school trip, long-standing gender conflicts escalate, leading to tensions among the students.

Even during the school trip, the ongoing gender role conflict persists, giving Yi Kyung some challenges.

The college entrance system changes so often that the students and the teachers both have a hard time.

Won Seok feels frustrated as he cannot get higher scores on his tests, regardless of how hard he studies.

Young Eun's classmates and teachers initiate fundraising when it's revealed that her mom is sick.

Seok Ju starts dating Seo Kyung from the electrical crafting club, who looks much like his first love.

Bok Man arranges an after-school marathon club, but the three bottom students are the only applicants.

Amidst rampant rumors that Jae Hyun and Jun Hee are dating, their love deepens even further.

Bok Man gives students in Division 11-5 homework, which is to write an introduction about their friends.

A female student has a baby in the school's bathroom. Da In, whose mother's a single mother, is affected.

Some new teachers, including a new homeroom teacher for Division 11-5, come to the school.

During the exam season, students are sensitive about their grades and ranks, and strange happenings occur.

Many students refuse to take makeup classes during the vacation. Some teachers are also against them.

Dal Sik and Na Young spend 100 days together dating, and they prepare for a special celebration.

Upon learning of the school's new hairstyle regulations, students decide to confront the school.

As the anniversary of his old friend Min Kyu's passing draws near, Se Chan finds himself battling insomnia.

The school demands the students to sign a form stating that they are aware of Hong Geun's mental illness.

As the Free Will initiative launches a popularity contest among school teachers, opinions diverge sharply.

Consumed by feelings of inferiority, Soo Hyun gives Yi Kyung a hard time ahead of a national math contest.

Upon Hong Geun's return, tension rises between Se Chan and Seok Ju as they grapple with differing approaches.

Yu Jin finds herself in a state of turmoil, overwhelmed by her uncontrollable crush on Seok Ju.

The launch of an online alumni service brings old classmates together. And illusions are shattered.

As the seniors finish their CSAT, the teachers, including Young Jin, initiate career counseling sessions.

To fill the vacant student president position, the school administration decides to organize a new election.

The friends navigate a group project to create a musical production led by Hye Ran, the termagant lady.

Motivated by a desire to gain her stepmother's approval, Soo Hyun decides to enter an essay contest.

With a little help from Soo Hyun, Da In and her friends track down a hacker among them in school.

When Da In discovers that Se Chan is leaving for the UK with his family, she becomes devastated.

After having a nightmare where Seok Ju dies, Yu Jin is terrified that it might come true.

Min Jae returns to the school as a college student, asking permission to observe the teacher's office.

After Se Chan leaves, a depressed Yi Kyung finds solace in a new friendship with Seung Min.

An anonymous letter from an unlikely author hinting at suicide is posted on the school website.

Ji Yoon uses Da In's poem as the lyrics for his band's new song and decides to participate in a rock festival.

Ji Hoon wants to work on his music, but his father is strongly against it. The rock festival is coming up.

The kids at school are curious about romantic relationships and physical intimacy between a man and a woman.

Jong Soo, the teacher, is having trouble with Seok Ju after Seok Ju got into a fight with some delinquents.

The news of Yi Kyung's father's business bankruptcy weighs heavily on the atmosphere of Division 11-5.

Kang San and his friends decide to embark on a spontaneous bicycle trip to Gangneung in Gangwon-do.

Won Seok falls ill with food poisoning after eating meat given to him by a stranger on their bicycle trip.

The students start their senior year, and they can hardly have fun like before. Da In plans a reunion.