Mi Jin had met Johan in a church she used to attend regularly and thus they became friends.
Mi Jin is a teenage girl who is found to be very beautiful by many of the other characters. She has a slim figured body and is pale skinned. Mi Jin has chestnut-brown hair with a fringe and she also has large, dark eyes.
In many chapters, she is shown wearing her school uniform but when she is not wearing her school uniform, she tends to wear nice and fashionable clothes, which sometimes tend to be pink.
Mi Jin used to wear her hair in two braids in the earlier chapters but later changed her signature hairstyle into a bun.
She dislikes fighting and believes there are better ways to solve problems. As she gets upset when Jin Sung gets into fights, she is part of the reason why Jin Sung has stopped acting aggressively. She is kind, caring and helpful. She is also very observant, as can be seen when she noticed that Jin Sung was getting repeatedly upset in the Sports Day as he could not beat Hyung Suk in any of the events. She enjoys studying in the library.
Mi Jin first meets the protagonist, Hyung Suk, on the streets after Hyung Suk, in his original body, had just gotten a haircut. Hyung Suk thought his haircut had made him very handsome, but he just looked like Kim Jung Un. When Hyung Suk finds Mi Jin looking at him, he thinks that she is interested in him, so he smiles at her.
Jin Sung sees Hyung Suk smile at Mi Jin and thinks he's propositioning her. He confronts Hyung Suk, and may have gotten into a fight if Mijin had not steered him away, telling him not to act aggressively in public. While walking away, Mijin smiles apologetically at Hyung Suk for Jin Sung's behaviour. Hyung Suk takes the smile for flirting and asks Mijin and Jin Sung out for coffee. Jin Sung punches Hyung Suk in the face while bystanders took pictures and uploaded them online.
On the first day of school, bullies are forcing Ji Ho to fan a magazine up and down because of the heat. When an unattractive girl tells them to stop because she was getting cold, the bullies laugh at her. However, when Mijin asks them to stop, the bullies stop immediately.
When Jin Sung goes to the convenience store where Hyung Suk works at night, he is upset because he thinks Mijin is attracted to Hyung Suk in his new body. It was also revealed that Chapter 2 was Jin Sung's date with Mijin. Moreover, Jin Sung had asked Mijin out, but she had refused. Jin Sung was so mad that he beat Hyung Suk in his original body up.
When Jin Sung's friends show off the picture of Hyung Suk and compliment Jin Sung's speed, Jin Sung tells them that he isn't proud of hitting Hyung Suk even though he actually wants them to speak up louder so Mijin would hear. He thinks that Mijin would think he is cool for being very strong. Instead, Mijin says that he hates the way Jin Sung fights all the time. She explains that in Chapter 2 Jin Sung had invited her to the movies only to get into a fight (with Hyung Suk). The girl chatting with Mijin tells her that Jin Sung used to be a rising boxer in middle school.
When Jin Sung's friend insults Hyung Suk's mother and Hyung Suk tells him he's gone too far, Jae Yeol, Jin Sung's friends, Mijin, and Ha Neul look surprised. Jin Sung, however, is outraged because Hyung Suk had made a fool of him in front of Mijin.
Jin Sung and the Ghost Lady
Mijin had forgotten her cell phone, and Jin Sung was accompanying her to school to retrieve it when they bumped into Vasco and Bum Jae, scaring Mijin. When Jin Sung asks what's so scary about coming to school, Mijin tells him of the story of the Ghost Lady, who prowls through the school on rainy days in search of her lost children. It turns out that Vasco was there to find the Ghost Lady because he wanted her to grant him a wish that people wouldn't call him stupid anymore. Jin Sung, trying to look cool in front of Mijin, makes fun of Vasco's superstition, only for Bum Jae to dare him to sign his name on the glass frame surrounding the portrait. Mijin, Bum Jae and Vasco waits for him in the classroom. When he returns, he tries to look brave in front of Mijin. The next morning, Mijin, Hyung Suk, Vasco and Bum Jae go to check out the signature only to find it on the window instead of on the portrait. Jin Sung faints and wets his pants. In the end, he explains that whether he had hallucinated due to fear or had actually seen a ghost, the important thing is that Mijin saw him wet his pants.
It has been revealed that Lee Jin Sung has a crush on her. She seems to be neutral, or even accepting of this, but still acts very shy about it. Jin Sung and Mi Jin care about each other a lot and often spend time with each other. Mi Jin dislikes when Jin Sung fights in public or makes a scene, often pulling him away from the conflict and scolding him for it later.
When the two of them go to the library together later, Jin Sung promises not to fight that day, but ends up getting into a conflict with a group of bullies at the library who decide to pick on him and eat the Honey BBQ chips Jin Sun brought to give to Mi Jin, which are her favorite. He lets it go at the insistence of Mi Jin, but ends up fighting the leader of the group when he gropes Mi Jin.
Mi Jin is a little upset that Jin Sun didn't keep his promise, but later that night in a text she hints that she is happy he defended and protected her and that she forgives him.
When Hyung Suk first met her in his original body, he thought she was flirting with him when she smiles at him. Actually, she was only trying to apologize for Jin Sung's aggressive behaviour. She is friendly with Hyung Suk in his new body, and is part of the friend group that he hangs out with.
Johan is Mi Jin's and Lee Jin Sung's childhood friend. She and Johan attended the same church. Johan also has a crush on Mi Jin. They were good friends.
- Mi Jin has a teddy bear charm connected to her phone, similar to the teddy bear toy she had when she was younger.