Seungeun was heading to a graduation trip with friends when he had an accident. No matter how much he tried, his phone wouldn't work. All his friends disappeared from his contact list, except for one new addition who responded.

"I will help you."

The hand that reached out from the light pulled him into another world, Dongak. The owner of the hand is Jincheong, the emperor of Dongak. He came through the emperor's mirror.
To return home, it seems he must become the emperor's concubine.

"But I'm a guy..? Can a man be a concubine?"

It's okay, because the emperor is a woman.