At Eighteen - Season 1
1 - The Nameless Kid, Choe Jun-u
Air Date: July 22, 2019
Not long after arriving at a new high school, where he's shown around by star student Ma Hwi-yeong, Choe Jun-u faces an unfair accusation.
2 - A Moment I Want to Run Away
Air Date: July 23, 2019
Jun-u prepares to transfer schools again. Yu Su-bin doesn't believe Jun-u took the watch. Hwi-yeong won't own up to what he did.
3 - It Always Rains on a Sad Day
Air Date: July 29, 2019
Jun-u beats out Hwi-yeong to pair up with Su-bin for a class assignment, and receives an urgent call about an old friend.
4 - Happiness and Sadness Come and Go Instantly
Air Date: July 30, 2019
Su-bin and Jun-u continue practicing their English for the upcoming evaluation. Sin Jeong-hu writes a letter, and makes a heartfelt apology.
5 - After that Long and Sad Day
Air Date: August 5, 2019
Jun-u's outburst of rage panics Hwi-yeong, who has something to cover up. O Han-kyeol visits someone who can testify to the truth.
6 - The Timing of Action and Reaction
Air Date: August 6, 2019
Fighting with her mother, Su-bin doesn't go home. Determined to reveal Hwi-yeong's true nature, Jun-u starts to gain insight into his behavior.
7 - Romeo and Juliet
Air Date: August 12, 2019
Su-bin and Jun-u can't stop thinking about each other -- but don't know what to do about it. Hwi-yeong agonizes over one wrong answer on a math test.
8 - The Moment of Your First Love
Air Date: August 13, 2019
Even as Su-bin learns she's not the only one who likes Jun-u, she's excited for their first date. Jo Sang-hun goes up against Hwi-yeong's parents.
9 - I'm Sorry
Air Date: August 19, 2019
Hwi-yeong sends Su-bin something that cuts her date with Jun-u short. Han-kyeol turns away a bribe. Yun Song-hui searches for a driver.
10 - The Night That Will Never Return
Air Date: August 20, 2019
When the class goes on a trip together, the students bring with them a tangled mess of relationship and personal dramas.
11 - The Emotions That I Got to Know Through You
Air Date: August 26, 2019
Han-kyeol deals with a petition to replace him. Hwi-yeong removes Su-bin from the tutor group, which bothers Song-hui more than it does her.
12 - Being More Mature Than Adults at the Age of 18
Air Date: August 27, 2019
A rumor about Hwi-yeong's grades being rigged spreads like wildfire. Su-bin hesitates to tell Song-hui something, and meets with her father.
13 - I Should Still Like You
Air Date: September 2, 2019
Finals approach, Song-hui's disapproval forces Su-bin and Jun-u apart, and Han-kyeol tracks down Hwi-yeong's old teacher.
14 - Happy Birthday to You
Air Date: September 3, 2019
Everyone worries when the rumor about Hwi-yeong gets him into real trouble. Jun-u tells Han-kyeol about his newfound goal.
15 - Ways to Embrace Your Scar
Air Date: September 9, 2019
Song-hui remains stubborn about Su-bin and Jun-u, who enters an art academy. The school board investigates Hwi-yeong's case.
16 - This Goodbye Isn't Forever
Air Date: September 10, 2019
Hwi-yeong makes peace with the others -- and himself. Jun-u realizes his mother's situation, and must break difficult news to Su-bin.