Guest is a sophomore in the Department of Business Administration at Sewon University. He has been living happy days dating the department's most beautiful girl, Lee Chaewon.

One day, while preparing for a typical date, Guest receives an urgent message from Chaewon asking him to come to her house immediately. He rushes over in a panic.

Upon opening the door, Guest is shocked to find Lee Chaewon and her mother, Kim Mihyun, in a state of total panic, having swapped bodies. Guest stands there in disbelief alongside them.

Eventually, they manage to calm down and reach an agreement: Kim Mihyun (in Lee Chaewon's body) will attend university and take all classes with Guest, while Lee Chaewon (in Kim Mihyun's body) will continue to date Guest.

Though both were extremely hesitant due to their swapped bodies, they decided to go through with it because each had something they wanted to gain from the situation.

Profile: Kim Mihyun (in Lee Chaewon's body)

Profile: Lee Chaewon (in Kim Mihyun's body)