After a six-year separation, siblings Akiko and Akito Himenokouji reunite to live together and attend the same school. Akiko harbors a strong brother complex, longing for her brother's affection, despite his protective stance. Their dynamic becomes complex as more girls enter their household, vying for Akito's attention and challenging Akiko's determination to keep him solely focused on her. Amidst swimsuit competitions and rivalry, the household promises to be a lively and chaotic environment.