Soccer-obsessed high school student Takanashi Rin leads a straightforward life until his father remarries, suddenly bringing three stepsisters into his home. The new arrivals are the beautiful twin sisters Rio and Hinano, along with their much younger sister Yume. Rio is a popular model who reigns as the queen of the school, while Hinano is a quiet, cool beauty who keeps others at a distance. Five-year-old Yume is the sweet youngest member of the family. Their cohabitation under the Takanashi roof sparks a string of lively, chaotic, and romantic daily events.

Rin navigates life with his strong-willed new sisters at home while also being surrounded by other girls at school: his childhood friend Meiyuu, the soccer club manager Senoo-senpai, and class representative Kawame-san. As the series progresses, a childhood friend of the twins, Asuka, appears and openly harbors feelings for Rio, further complicating the relationships. The central question running through the story is which of these girls will ultimately become Rin's bride.

The narrative follows Rin and the sisters as they grow closer, confront their feelings, and face individual challenges. A key arc involves Hinano's pursuit of her dreams and Rin's internal struggle between supporting her and wanting to stay by her side. Rio, understanding both her brother and sister, takes action to push them toward honesty. The story culminates in Rin finally confronting his own heart and racing to reach Hinano, leading to the resolution of who the future bride of the Takanashi household will be.