Daikichi Kawachi, a 30-year-old bachelor working in a respectable job, is aimlessly wandering through life when his grandfather suddenly passes away. Upon returning to the family home to pay his respects, he meets Rin, an illegitimate daughter of his grandfather that he never knew existed. The shy and unapproachable girl is ostracized by her fathers relatives who refuse to take care of her after his death. Daikichi, angered by their coldness towards Rin, announces that he will take her in despite being a young single man with no prior childcare experience. Usagi Drop follows the journey of Daikichi as he raises Rin with his gentle and affectionate nature while exploring the warmth and interdependence at the heart of a happy family.