After her divorced parents remarry, Yui returns to her hometown for the first time in eight years. She has not seen her older brother, Hayato, during that time, so she is amazed to see how popular and grown up he has become. She also bumps into her childhood friend, Ritsu, who she remembers as a crybaby, and almost doesn't recognize him. Now living with her brother again, she can't help but notice her heart fluttering with each interaction. Does this mean she might like him?! Knowing how taboo these thoughts are, Ritsu suggests he and Yui date as a way to nip her feelings for Hayato in the bud. Yet this family tree may not actually be as simple as it seems...