Infiltrate! Chaebol By Fortune_Cookie

Lee Dakyeong is a member of an elite gang. When he learned that his boss, who was also a figure he considered like a mother, had died, he was very sad. Later he finds out that the death of his boss has implicated Chairman Lee. Dakyeong also tried every way to get revenge. But that's not easy considering Chairman Lee is hiding behind the Sayoung Group. Just as Dakyeong is about to give up, he hears about Chairman Lee's son's whereabouts.
Ready to sacrifice anything, including his own life, Dakyeong decides to go undercover as a transfer student at a conglomerate high school, where Chairman Lee's son is.