High school student Takahashi Kotori is a cheerful, ordinary girl with one major problem: she is deeply in debt because of money her mother left behind before leaving the family. This financial hardship forces her to work, but she is fired from her part-time job. Desperate, she notices a poster seeking a housekeeper. She applies and is immediately called for an interview. Upon arriving at the house, she discovers it is a complete mess, and the residents are three handsome brothers.

The house belongs to the Manabe family. The parents live overseas, and the only condition for hiring a housekeeper, imposed by the parents, is a strict prohibition on having a romantic relationship with any of the three brothers. Breaking this rule means instant dismissal. In the past, this rule was broken many times, leading to previous housekeepers being fired. Kotori prioritizes money over romance and accepts the condition. However, she soon finds herself in a chaotic situation as all three brothers individually start proposing relationships and seducing her, creating a battle between a working student who cannot afford to fall in love and three handsome brothers who want to.

The three brothers are all distinct. The eldest, Asahi, is a high school senior and a professional shogi player. The second brother, Mahiru, is also a high school student and the ace of the volleyball club. The youngest, Yuhi, is a first-year high school student and a 2.5-dimensional stage actor. At first, only Asahi and Yuhi actively court Kotori, while Mahiru seems uninterested. This changes after Mahiru falls ill and Kotori nurses him through the night, sparking his direct and intense interest in her.

As the story progresses, Kotori finds herself emotionally moved after watching Mahiru passionately play volleyball, leading to a complicated shift in her feelings despite the work contract. Her relationship with Mahiru deepens, and they eventually confess their love for each other. However, their relationship is discovered by Mahiru's mother. Instead of simply firing Kotori, Mahiru's mother issues a challenge: she will allow them to date if Mahiru can lead his team to the top four at the Spring High volleyball tournament. Simultaneously, Kotori is pressured to turn Mahiru down, leading to a major decision point for her and the conclusion of her love story with Mahiru.