"Mr. Underwear" tells the story of a young man named "Ajing" who has a funny double life. The protagonist seamlessly switches between dual identities, works tirelessly, and is full of the inspirational spirit of "knowing it is impossible but doing it anyway". In the underwear company, Ajing is cute and timid, experiencing the ups and downs of being a newcomer in the workplace. In the family business, Ajing transforms into a domineering president, calm and wise, and fights wits and courage with the "shrimp soldiers and crab generals" headed by two veterans. Her alternative wisdom that does not play by the rules can always easily play with the veterans who are shrewd and funny, and resolve crises in unexpected and humorous ways time and time again.