Su-Yong is short. He is about ten centimeters shorter than Hikaru, whom he is a years younger than, and about thirty centimeters shorter than Yongha, whom he is three years younger than. His hair is black, almost a dark blue color. It is cut in a "mushroom"-style bowl cut. He is often seen wearing a backwards cap. In informal settings, he is seen often in shorts with a T-shirt or sweatshirt. In formal settings, he wears a dark suit and a black tie.
After losing match upon match in Korea, he loses his edge and becomes antisocial. He was sent to stay with his uncle in Japan, who owns a Go salon in hopes that he will regain his calm and his focus.
When Hikaru enters the salon and reveals that he is an insei, Su-yeong says that he doesn't need to bother playing Hikaru because yeon'gusaeng are far superior to insei in terms of skill and determination. After losing the game that he was certain he would win, he begins to cry and asks Hikaru for his name in what little Japanese he knows. He swears that one day he will have a rematch with Hikaru, and that when that day comes, it will be Hikaru who has to remember his name.
In the three years that Su-yeong is absent from the story, he returns to Korea and dedicates himself fully to bettering his game. He becomes a pro, and gains fame after defeating a Korean 9-dan. He learns Japanese, mostly out of the desire to talk to Hikaru and tell him, "My name is Hong Su-yeong!".
Hokuto Cup Arc
Su-yeong reappears as one of the Korean representatives of the Hokuto Cup. He is excited to see Hikaru again, and expects to play him in one of the rounds. However, due to a change of positions on Hikaru's team, Hikaru ends up facing Ko Yeong-ha, and Su-yeong plays Kiyoharu Yashiro, whom he defeats. Although disappointed in being unable to play Hikaru, he understands Hikaru's motives for wanting to play Yongha. Due to miscommunication, Yongha is accused of insulting Honinbou Shuusaku, the renowned Go player for whom Fujiwara-no-Sai had played every game, angering Hikaru. Trying to settle out the tension, Su-yeong discovers what Yongha had really meant, but Yongha, interested to see what Hikaru will do, forbids Su-yeong from telling Hikaru.