Kong Young-soo x Seo Seo-yoon, Kong Yi-young x Gye Yi-soo.\n\nKong Young-soo, who turns 30, and her younger sister Kong Yi-young, who is starting her first job. Their relationship is too distant to be called close, yet too affectionate to be called strangers.\n\nKong Young-soo meets her one-night partner Seo Seo-yoon due to an action taken by her friend Seob Da-jeong during a drinking party. Contrary to their conversations through the app, Seo-yoon discovers that Young-soo has no BDSM experience and pushes her into a corner. However, for some unknown reason, with a mix of sympathy and curiosity, Seo-yoon engages in light play with Young-soo.\n\nThe sensitive neighbor Gye Yi-soo, who moves in next door to Kong Yi-young, constantly sticks post-it notes on her front door complaining about the noise, saying that Yi-young is too loud every day. The post-it notes that appear without fail every day cause Yi-young considerable stress. After drinking with her close sister Da-jeong, who lives in the opposite neighboring house, Yi-young, in a fit of anger, writes a sarcastic reply on a post-it and sticks it on Yi-soo's front door.\n\nKong Yi-young meets Gye Yi-soo as a manager at her first job, while Kong Young-soo welcomes Seo Seo-yoon as a new employee.\n\nThe different romantic views of the two sisters. How will their romantic relationships unfold?