After breaking up with her boyfriend Natsui on Christmas Eve, Shino Tadokoro has hit rock bottom. Meanwhile, her brother Tamotsu is on cloud nine after the college girl Erina stole his first kiss on that same Christmas Eve. The relationship between the siblings changes, and their dynamic shifts. Gradually, Tamotsu turns his attention to women, and Shino turns hers to her dream.... Catch the dramatic developments in today's most exciting family manga as it shows the hardship and joy of having a brother or sister!