Sung-Jin is a well-kept man that wears large eyeglasses at all times. He has relatively long light-purple hair and lavender eyes.
Sung-Jin seems friendly at first but in reality he is manipulative and condescending. He asked Mi-Ra to marry him because he wanted to get her sword, a National Treasure, so that he could give it to Nox. He must be very smart since he is the chairman of a very profitable organization.
He spots Mi-Ra walking around with Jin Mo-Ri and Han Dae-Wi one day and sees her sword and recognizes it as a sword of value. When Mi-Ra nd Mo-Ri take after another purse-snatcher, Sung-Jin pursues as well. He takes Mi-Ra's sword to take down the purse snatcher and confirms it to be the National Treasure, Bong-Seon. He asks Mi-Ra for her hand in marriage right there. He goes to Mi-Ra's uncle for his permission until Mi-Ra eventually accepts out of financial need.
At the wedding, he reveals his sadistic nature to Mi-Ra's uncle when he attempts to halt the wedding. After getting Mi-Ra's uncle and cousin taken away, he stands on the altar with Mi-Ra about to say their vows when Mo-Ri and Dae-Wi come bursting in to stop her from marrying. After taking a while to convince her, Mi-Ra admits she doesn't want to marry him to his condemnation. He then attacks her with a sword of his own only to get cut down by Mi-Ra's Moon Light Sword Style. He takes her National Treasure and then flees while he can.
Enhanced Speed: He is quick enough to earn Mo-Ri's admiration and even surprises him at one point.
Swordsmanship: He appears to be at least proficient with a sword.
Samurai: His charyeok takes the form of a samurai and is the fourth one seen in the series.