Soo Jimin was just a regular tom boy. She had talent with singing and lived with her best friend. One day, a man pulled her off the street and had her audition for an entertainment company to save his job, and the entertainment. They accepted her as a new trainee but wanted her to immediately debut in the next month. But, there were a few problems. One of them was, they think she's a guy. She was so much of a tom boy, people immediately mistaken her as a male. The other problem, since she's accepted so soon and out of random, she is forced to dorm with one of the hottest rookie groups, Monsta X. How does she keep hidden from the group? How will her relationship with the members turn out? She's a girl in a guys' dorm. Do they know? Does she stay? Or is everything going to be ruined for her career, life, and theirs?