Takagi Mamoru works in a claiming center and has to deal everyday with unhappy customers. A little while after being reunited with his close friend Sasakura, this one dies, leaving his six year old twins alone. Although their father wanted them to always be together, their remaining family separate the twins in two households, making the boy run away. Takagi, who's been worried about the kids help finding the boy and takes them to his place so they can be together. And along the kids comes a stray talking dog.
'Marumo' is the way the kids call Takagi instead of Mamoru.