Joo Yeon-ho works as a private academy instructor. One day, his former tutoring student Ahn Ji-hye — whom he hadn’t seen in four years — comes back into his life, completely unrecognizable from the girl he once knew. Unable to refuse due to circumstances, he finds himself reluctantly agreeing to an energy-draining cohabitation with her… The diligent and bright student he once remembered is nowhere to be found. Ji-hye has transformed into a total immature mess, acting like a carefree, irresponsible kid with no sense of adult responsibility!