Yoon Heesoo is the prodigal illegitimate child of Daeyoon Group, a leading domestic conglomerate.

"From now on, I'll be in charge of your behavioral education."
"……."
"Please don't let anyone else concern themselves with it."

Secretary Kang Joochan,who was assigned to monitor and control every move of Heesoo, and Heesoo, the young master, desperate to break free from him. For 10 years, they've been taming each other and have thus coexisted.