He has a skinny, lanky body and a long cleft chin. His black hair is pointed up at his bangs.
Second Hand Rana
Hyun Do, his two friends, and Park Hyung Suk are initially recruited by Jin Sung to help him confront the scammer who took his money, but after running into and recruiting Vasco, Hyun Do and the other two lackeys were told to stay behind with Vasco reasoning that too many of them would make the situation more complicated.
Autumn Boot Camp
On the bus to boot camp, Hyun Do, along with Park Ha Neul and Kim Yui, ecstaticly invite Hyung Suk to sit with them (along with Jin Sung, Ji Ho, and Mi Jin) in the back of the bus where they play some games to pass time, much to Hyung Suk's pleasure.
Later that night during the curfew, Hyun Do brings Hyung Suk and Jin Sung to a place where his two cronies and the Beauty Department girls (hoping to hang out with Hyung Suk and Jin Sung) were waiting for them. But both Hyung Suk and Jin Sung made excuses to get themselves out of there, much to the disappointment of Hyun Do and the girls. He, along with the two cronies and the Beauty Department girls were later caught by the camp instructors and forced to do squats as punishment.
The next night, Hyun Do assists Hyunk Suk, Ji Ho, and Ha Neul in searching for Mi Jin and Jin Sung. He suggest that they might just be hanging out and will return soon, but they keep searching regardless. Along with the police, they eventually find Jin Sung beating up Heemin Kim after the latter attempted to rape Mi Jin.
Hyun Do offers Park Tae Joon to make a video with him on Pacebook, which he accepts. He then tries to offer Hyung Suk to join him (hoping that his looks will get them views), but Jin Sung tells him to shut up. Tired of being told what to do, Hyun Do reminds him that he spent his own money to buy things for him and that he should be thankful. Just before they're about to fight, they are separated as Hyun Do shouts that Jin Sung has no friends, but rather underlings who do things for him.
In the Pacebook video Hyun Do makes with Tae Joon, they call out the gangster Shin Dae Hoon, gaining them popularity. Tae Joon worries about the possibility that Dae Hoon will respond, but Hyun Do assures that it's all going to be alright. As they make more videos targeting Dae Hoon which gets more and more attention every time, Dae Hoon finally responds after they make fun of his mom, saying that he will find and catch them, knowing that they both go to Jae Won High.