Katakura Kippei adalah playboy terkenal di SMA-nya. Menghabiskan hari-harinya menggoda wanita yang ia lihat, tanggung jawab adalah hal terakhir dalam pikirannya. Hidupnya berubah ketika dirinya diberikan tugas merawat secara fulltime sepupunya yang masih berumur 5 tahun. Bibi Kippei di Miyako yang lama menghilang, tiba-tiba muncul dengan meninggalkan sepupunya, Yuzuyu. Dengan kurangnya Kippei tentang tanggung jawab dan pengetahuan anak dan juga hati Yuzuyu yang terluka karena hilangnya ibunya, waktu mereka habiskan bersama-sama.

Katakura Kippei is in every way a high school playboy. Spending his days flirting with any female he can see, responsibility is the last thing on his mind. Life takes an unexpected turn for him as one day he returns home to find himself with the fulltime task of caring for his 5-year-old cousin. Kippei’s aunt Miyako had disappeared, appearing to have abandoned his cousin, Yuzuyu. With Kippei’s lack of responsibility and knowledge of childcare and Yuzuyu’s injured heart with the disappearance of her mother, their time together is in for a bumpy ride.