Five family members, one legendary fish. The family are dedicated fishing enthusiasts who have set out together for the secret spot where the Kawa no Nushi — the master of the river — is said to live. Each has a different reason for making the trip: the son is looking for a friend who went searching for the fish and never returned; the father hopes a successful catch will repair the distance that opened after his rod broke; the mother has heard that eating the Kawa no Nushi restores ten years of youth; the older sister has decided fishing is the diet plan she has been missing; and the youngest is simply determined to become the greatest fisherman in the world, regardless of her age. They are after the same fish for entirely different reasons.