Yeon Si-Eun is a student at Eunjang High School and one of the most academically gifted students in his year. He is known for his exceptional intelligence, quiet demeanor, sharp observations, and intimidatingly calm personality. He has a naturally slim build and doesn't look particularly threatening, which causes people to underestimate him. However, Si-Eun is far more dangerous then he appears.

He was in class one day with his friends, and all the sudden it's mentioned that there will be a new student.