He was once a passionate educator, but grew weary of teaching dim-witted students, eventually becoming a materialistic man who despises fools. However, looking at his behavior throughout the story, it seems he was never particularly kind to begin with. He is currently the most villainous character, having scored a perfect 40 on a psychopathy test. He frequently appeared tormenting the slow-witted Gyeong-tae, extorting money from Kang Gyeong-ja through false hope while hurling verbal abuse and threats at Gyeong-tae. In the 'CSAT D-10' episode, while grocery shopping for his wife, he meets Bae Hyeok-jae. The two mock parents who send their children to academies without even checking resumes, saying, 'I feel sorry for the kids because of their stupid parents.' They are overheard by Gyeong-tae, who was there to buy eggs. When Kang Gyeong-ja finds out the truth and visits the academy the day before the exam to ask for a refund for the special classes, he reacts with indignation and mocks both her and Gyeong-tae. After the CSAT, parents including Kang Gyeong-ja report him as a group. Even when the police enter the academy to arrest him, he brazenly denies everything, claiming there is no evidence.