Hitomi's grandfather plans on making Hitomi inherit everything, but it comes with a price: living with her ex-girlfriend (from ten years ago) for one month. The ex-girlfriend is none other than Kim Chaewon, a doctor. Their past is revealed and the wounds from their breakup become fresh once more. Can Hitomi survive the month without falling in love with Chaewon or will Chaewon manage to make Hitomi fall for her again?