He has light brown hair, slightly thick eyebrows, and big, round, brown eyes. A very good-looking kid.
He is usually seen wearing a yellow/orange and white striped jacket, blue pants and white sneakers. Other clothing are:
In gym class, he wears a white shirt decorated with green outlines and green shorts. Also, wearing his usual sneakers.
In the bath house, he wears a towel just below his waist line, as seen in the episode: "Tell me you like me".
Yunseok Lee is very energetic, sporty and high-spirited kid. He is very mischievous and loud. Within Jadoo's circle of friends, he is her frenemy. Very boastful and sometimes he is a bit show-off. He was often teasing and "bullying" Jadoo, but he actually has a crush on her. He has a great passion of hating Seonghun Chang, because he also like Jadoo. And sometimes when Seonghun Chang was being too close to her, Yunseok Lee becomes really jealous.
- He is also a pretty famous kid at school because of his handsomeness. In the episode "Whom the Valentine Chocolate is?", he got lots of chocolate from his fan girls.
- In the episode "Whom the Valentine Chocolate is?" it showed clearly that Yunseok Lee has a crush on Jadoo.
- In the episode "tell me you like me" Yunseok bullies Jadoo and accidentaly takes a picture of her "doing buisness" at the end of this episode Jadoo gets bullied by a boy and at the really end Yunseok says to this boy to get away from Jadoo or "he'll get it" this boy asks why? Yunseok answers because Jadoo's pretty - <3
- in season 2 "You like me?" episode Yungseok approves and shows Jadoo he has a crush on her.... but this U Jadoo may ruin his crush on Jadoo Choi since Yunseok seems to like her when he saw her
- He showed his sentimental side when he returned Seonghun Chang's snail (Green) to him after he was beated to a pulp by Jadoo in the episode, "I like Jadoo" .
- He was shown to be a perv at the end of the episode, "Tell me you like me.".
Seonghun Chang- He hates him for being so close to Jadoo, and also he thought of him as a girly kid, since he commented, "He looks like a girls..." he also hates him for punching him on the face.
Jadoo Choi- Though he bullies her, he really has crush on Jadoo.
Minji Kim- It showed that Minji has a crush on Yeongsun in an episode, and she couldn't stop thinking of him.
Dol Dol- It is shown that Yeonsun and Dol Dol are close friends, because they often talk to each other.