He is water, fire, wind, light, and darkness. And he was once human. His real name is Kim Shin. His current alias is Yoo Shin-jae. A military official of Goryeo, he lost his life due to treason a thousand years ago and returned to this world as a Goblin due to a god's curse, existing for hundreds of years. He is 939 years old. As of 2016, he is the actual owner of the entire Cheonwoo Group, having delegated management rights to the descendants of the Yoo family, his vassals. He lives under aliases like Yoo Shin-jae and Yoo Jae-shin, hiding himself within the world and acting as a guardian deity for humans. He usually behaves in a dignified, calm, and mature manner, but upon closer inspection, he often says stinging words and can be narrow-minded and childish, getting sulky or jealous easily. Consequently, power struggles with the Grim Reaper are a daily occurrence, and he frequently bickers with Eun-tak. However, he has a likable side, such as apologizing immediately if he feels he has made a slip of the tongue. He rarely interferes in human life and death, but when he helps humans as a guardian deity, he performs miracles for those reaching the threshold of life, mainly young children. As in the legends of Goblins, he is actually afraid of horse blood. He possesses many abilities that he boasts about himself. Teleportation (from door to door), psychokinesis, immortality, weather manipulation, time stop, summoning, sword energy, pyrokinesis, superhuman strength, etc. Due to his superhuman physical abilities and durability, he has lived for 939 years and is now entering his 940th. Even when he collides with a truck and the impact causes the truck and the cars behind it to fly off and be destroyed, he remains perfectly fine. Furthermore, since he doesn't die in the first place, he doesn't get injured or fall ill. When he asked for the drink the Grim Reaper was holding, saying he thought he had a gastric ulcer, the Grim Reaper replied, "You wouldn't die even without a stomach. You just wouldn't be able to eat." Human medicine doesn't have much effect on Goblins, but he takes it frequently. He is extremely vulnerable to alcohol. Very, very much so. Only the Goblin's Bride can pull out the sword stuck in his chest, ending his eternal life and allowing him to return to nothingness. Tired of his long immortality, Kim Shin wandered in search of the Goblin's Bride who could see the sword in his chest, and eventually met Ji Eun-tak, the daughter of a woman he saved 20 years ago. At first, he didn't believe Eun-tak could see the sword and denied she was the bride, but he fell in love at first sight with her bright smile. He takes medication for nervous breakdowns, bipolar disorder, and insomnia when his emotions are unstable. Also, when he watches horror movies, he screams and gets scared as much as anyone. He has a strong competitive streak, attempting claw machines multiple times, but he fails to win anything. Perhaps because of this, he is so similar to humans that he looks just like one when he isn't using his powers. He isn't particularly handsome, but he isn't ugly either. He has the appearance of someone in their mid-30s. However, he seems quite confident in his looks.

Somehow, he ended up renting a room in the Goblin's house and living with him. They bicker so much that there isn't a day they don't fight, but they gradually develop a friendship through their shared history. He is absent-minded and quirky in front of the woman he likes, but he is serious and sharp when he works. He acts prickly toward the Goblin and Ji Eun-tak. His profession is a Grim Reaper and the owner of a tea house for the deceased. In terms of abilities, he is mentioned to be similar to or slightly weaker than the Goblin, but he is shown to have his own unique powers. However, using his powers for personal matters is prohibited, and if he violates this, he will be disciplined by the Grim Reaper Department's audit team. He is somewhat overshadowed by Kim Shin, who shows incredible physical abilities and durability in the story, but the Grim Reaper also has superhuman physical abilities and durability. If he speaks while looking into the other person's eyes, he can manipulate their mind as if he were hypnotizing them. He uses this to change the memories of humans who have encountered mysterious events or to clean up the messes Kim Shin makes. However, if the hypnotic words he uses when performing mind manipulation contradict the other person's thoughts, the mind manipulation effect cannot occur.