Daikichi's maternal grandfather and Rin's father.

Going home from his grandfather's funeral, thirty-year-old Daikichi is floored to discover that the old man had an illegitimate child with a younger lover. The rest of his family is equally shocked and embarrassed by this surprise development, and not one of them wants anything to do with the silent little girl, Rin Kaga. In a fit of anger, Daikichi decides to take her in himself. As Daikichi nurtures Rin, he started to understand the struggle while at the same time the joy of parenting.<br>
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(Source: Anime News Network)

When 30-year-old Daikichi returns home for his grandfather's funeral he meets an unfamiliar child in the garden. His mother explains that Rin is his grandfather's illegitimate daughter by an unknown mother. The girl is an embarrassment to all his relatives and nobody wants to take her in because of the scandal. Annoyed by their attitude, Daikichi decides to take care of Rin himself, even though he is single and has no experience raising a child.

Souichi Kaga