Season 1[]
Dongseok is first introduced as one of the photographers of Happily Married Studios. He is the studio where the other photographers are sitting shirtless. Dongseok Oh asks 244 if he wants to see what they shot, and 244 says that animals mating is the same regardless. They are having trouble finding a candidate for the next one, and 244 suggests Rumi Yeo. He says it doesn't matter how young she is, because animals are animals. The photographer asks if he was nice to Rumi because he wanted her to star in the video, but 244 says he treats all animals the same.[1]
Dongseok later calls Wangguk over and asks if he knows why he hired him. Dongseok knew about Wangguk's criminal past, and he wanted to help him find a job in his field since nobody would hire an ex-convict. He asks Wangguk if he wants to make a lot of money, and Wangguk asks what kind of job he'd be doing. Rumi appears and asks if it's time for the shoot before heading to the changing room. Dongseok hands Wangguk a bathing suit and tells him to give it to Rumi. He refuses to tell him what kind of video they will be shooting, except that it will be X rated. Dongseok explains that their studio coerces women into these X rated videos through intimidation and using contracts that look legal. The women usually go along with it, and are too scared to say no. Dongseok tells Wangguk that if he tells anyone, he may disappear of the face of the Earth.
Dongseok asks if Wangguk gave her the bathing suit when he returns, and Wangguk tells him that he isn't going to. He says that he doesn't regret his actions, and that they should just fight him since the song already started.[2] Wangguk beats up most of the criminals. He recalls his coach mentioning a prodigy of his old boxing team Chungui, who happened to be Dongseok Oh he is fighting now. For that reason the coach never called Wangguk a prodigy, but a freak. Dongseok is a slugger with the agility of an out-boxer, and it shows. Wangguk finds himself overpowered by Dongseok's blows. He hits Dongseok on the top of the foot and manages to gain some distance. When 244 shows up, Wangguk is overpowered and dragged away.[3]
Dongseok gets a request from 244 to bring him all the information he can find about Hobin, in order to take revenge.[4]244 goes to a warehouse full of bloody bags. Dongseok says that several men were arrested, but since they were illegal immigrants it probably would lead to nowhere. He is not worried about Hobin and the company reporting him, since no bodily damage happened, and they are too scared of the consequences to do so. Dongseok asks Nameless why he didn't kill Samdak and bring the editor. The man says that Samdak was staring at the trigger, and calculating how to dodge the bullet. [5]
Dongseok is punishing one of the members of his team for causing errors with transportation. 244 arrives with Nameless and lets them know that the overseas company will be arriving in 90 days from Thailand. [6]Dongseok overhears Gyeoul's intrusion and tells his men to close the door of the warehouse. She managed to escape Dongseok by hiding in the bag of corpses.[7] When giving his report Dongseok tells 244 that Seongjun's secret ally was Hye-yeon Hwang. However, they don't want to hurt her since she is from a troublesome lineage. 244 ignores this and tells Dongseok to take care of the situation.[8]
Dongseok is next seen on the port waiting for the ship to arrive. [9]Jeongtae Park "The Dog Butcher" tells Dongseok that he will handle the situation. Dongseok calls 244 and asks what to do about them. 244 says that he will spin a narrative that the Yoo Hobin company attacked a gang for views. Min-soo runs to Dongseok and says that the Yoo Hobin company are too strong, and all of their men are going down. Dongseok hits Min-soo to the ground and says that he shouldn't worry so much. He slicks his hair back and saunters towards Wangguk, who is thankful they get to finally fight.[10]
Dongseok tells Wangguk that he has one more chance to set things straight and not be punished for his actions. Wangguk ignores him to call Rumi and tell her that he loves her, and they should meet up for coffee soon. Wangguk starts fighting Oh Dongseok, and he is dodging most of his moves. He recalls his coach saying that Dongseok only knows simple moves: to hit hard and run. However, Dongseok is a genius fighter, and he never needed to learn anything more. His coach tells Wangguk that he has something that Dongseok lacks: effort and technique.
Wangguk hits Dongseok many times with a powerful counter, but Dongseok copies the move and Wangguk tumbles. He tells Wangguk that the reason geniuses reign in boxing is because all of the hard workers died off. Wangguk punches Dongseok's cigarette and tells him that they didn't come without a plan.[11]Despite his reputation as the strongest member of CUD, Dongseok starts to get demoralised at Wangguk's continuous beatings. Wangguk keeps on hitting Dongseok until he collapses, and Rumi is safe again.[12]