Wears round glasses. He and Chan-bi liked each other before she lost her memory, and they started dating after falling for each other again. They haven't been together long. He's quite handsome and takes good care of his friends. A 2nd-year student in Class 3 at Moksan High. He lives in the same house as his niece Da-sol and her mother. He is Da-sol's uncle. Da-sol calls him 'Uncle'. He is very close with Da-sol. He reads two books to Da-sol every morning. He is the one who bought Chan-bi's umbrella, which she treasures dearly. He is very good at studying. However, before her memory loss, Chan-bi was actually better at studying than him. He has been shown going to the baseball stadium with Da-sol. He seems to be a hardcore fan, even going to watch games live during exam periods. Judging by the uniform colors, he appears to be a Samsung Lions fan. He has been friends with Chae Dong-wook and Seonwoo Hyuk since their 1st year of high school, and became friends with Baek Chan-bi, Ji Hye-rim, and Oh Da-geun in their 2nd year. He is the most frequent regular at the pho restaurant in front of the school. He is extremely kind and helps his friends a lot. Only Dong-wook and Hyuk call him 'Kkang-oh'. He successfully booked tickets for an idol concert Chan-bi wanted to go to, and has a history of successfully ticketing for IU concerts, so he seems to have a talent for it. Chan-bi's boyfriend.

She speaks in a cool or friendly tone to everyone except Kang Gyeon-oh. When she sees Gyeon-oh, her face turns red and she occasionally stammers. She lost a year's worth of memories after being hit on the head by a falling keg while working part-time. She has recovered some memories through her old notebooks and phone photos. She remembers her middle school friends and is now catching up on her studies and getting along with her friends like before. She likes Kang Gyeon-oh and they are currently dating, though not for long. She is incredibly beautiful and a 2nd-year student in Class 3 at Moksan High. She has the kind of beauty that anyone would fall for at first sight. She always carries the umbrella Gyeon-oh gave her when it rains and treasures it. The umbrella was given to her before she lost her memory, but she found out it was from him because Gyeon-oh told her. She hates it when her older brother, Baek Yong-ju, gets suspicious of her relationship with any guy near her. She has long black hair. There is a very, very small scar on the top left of her forehead from the keg. No one knows about it except for friends of several years, and it's not noticeable. Gyeon-oh, Oh Da-geun, and Ji Hye-rim know about it. She frequently goes to study rooms and is working hard on her academics. She is close with Oh Da-geun, Ji Hye-rim, Seonwoo Hyuk, and Chae Dong-wook. They feel like best friends. She is smart. She plays well with Da-sol, so Da-sol calls her 'Auntie'. A regular at the pho restaurant in front of the school. She often eats the spicy pho. She used to live in a studio apartment, but because the neighbor was so filthy, it became infested with cockroaches, so she moved out and into the dormitory. She has an idol she likes. Gyeon-oh's girlfriend.

He is a bit quiet and not very active, but whenever there's talk of going out, mood-makers like Ji Hye-rim or Seonwoo Hyuk drag him along. He cares about his friends so much that he even transferred schools just to be with them. Contrary to his vibe, he doesn't seem to be very good at studying. A handsome guy with black hair. A 2nd-year student in Class 3 at Moksan High.

He seems like the type who would be good at PE. He is very bright and feels like he has a screw loose somewhere. He is dating Min Hye-ju. His friends worry about his love life because of things Min Hye-ju has said, but he says he's fine. He keeps his promises to his girlfriend. In reality, Hye-ju just cares too much, which leads to some harsh words occasionally, but there are no major issues. A mood-maker. A 2nd-year student in Class 3 at Moksan High.

Baek Chan-bi's best friend. She is pretty. She seems to have good chemistry with Seonwoo Hyuk, but she hangs out with Chae Dong-wook more. Of course, she spends the most time with Oh Da-geun and Baek Chan-bi. She isn't very good at studying. She is extremely bright, loud, and has a screw loose. She meddles a lot in other people's romances. She's the type who claims to be helping a friend's love life but is actually just enjoying the drama. However, she is actually very helpful in connecting people, often doing things like putting two people together and then stepping back to watch their reaction. She seems to prioritize her own fun above all else. She loves hanging out. A 2nd-year student in Class 3 at Moksan High.

Her friends call her 'Oh-da'. For some reason, she always has a lot of snacks. She is great at holding her breath; she's likely a high-level swimmer. She is a laid-back, easygoing friend. She has a boyfriend. A 2nd-year student in Class 3 at Moksan High.

Gyeon-oh's middle school friend who helped him a lot back then. She has a short bob cut and occasionally gets ear piercings when she's angry; she currently has three on each side. She is pretty. She is good at setting people up on blind dates. A 2nd-year student at Haeil High. She is close to Gyeon-oh in a 'best friend' kind of way.

Seonwoo Hyuk's girlfriend. She seemed to have a difficult personality, but it turns out it's just because she likes Hyuk so much. A 2nd-year student at Haeil High. Close friends with Son Cheong-ah.

Baek Chan-bi's older brother. Incredibly handsome. He is a secret 'sister-lover' type, so he picks her up when it rains and she doesn't have an umbrella, and waits for her at the terminal when she returns from trips with friends. He cares about Chan-bi immensely. If there's a guy near Chan-bi, he immediately gets suspicious. He's the type to give people 'that look', you know?

Kang Gyeon-oh's niece. She follows Kang Gyeon-oh very, very, very much. She loves reading, so she asks Gyeon-oh to read her books every morning and before bed. She's probably good at studying, right? Everything she does is very cute. She also follows Baek Chan-bi well because Chan-bi used to play with her a lot and they've become close again recently. She calls Kang Gyeon-oh 'Uncle' and Baek Chan-bi 'Auntie'.