Daikichi learns that his recently deceased grandfather has an illegitimate daughter with an unknown mother. The girl's name is Rin and she is just 6 years old. Everybody in Daikichi's family looks at the girl as an embarrassment and wants no part of her. Daikichi, annoyed by his family's attitude, decides to raise Rin by himself. Even though Daikichi himself has no experience raising a child and is still single.

年仅6岁的小女孩鹿贺凛（松浦愛弓 配音）失去了最爱的爷爷宋一（有川博 配音），据说她是宋一的私生女，这个暧昧的身份成为鹿贺家的耻辱和负担。但是在葬礼上，凛却遇到了她生命中最重要的人——某服装公司的30岁单身男子河地大吉（土田大 配音），他是宋一的亲外孙。面对遭受家人排斥的小阿姨，大吉毅然承担起了照顾凛的重任。为了凛，大吉改变着自己的生活，牺牲了事业和爱情，相伴走过无数个平凡岁月。随着“女儿”一天天长大，大吉和凛的感情日益加深，彼此内心中的牵绊不可替代…… 本片根据宇仁田由美的同名人气漫画改编。