Do Kyung-soo (D.O. of EXO) was initially offered the role but declined, paving the way for Lee Do-hyun. His performance is widely considered a breakout role. He perfectly captures the nuance of an older man trapped in a younger body—using formal language, displaying maturity, and showing fatherly concern in a high school setting. Equally compelling is Kim Ha-neul as Jung Da-jung, the wife, whose portrayal of a woman trying to find her identity beyond being a wife and mother is deeply resonant.