Masaru and the Hayase family move from the city center to the suburbs, surrounded by abundant nature. Two fishing hooks are found inside a black sea bream delivered as a housewarming gift. The hooks tell the story of a fierce battle between a fisherman and a black sea bream. Fascinated by the fierce battle between man and fish, Masaru makes his own fishing equipment and heads out to a nearby river, but...!?

This is a story of fishing and friendship full of adventure for young Masaru and his friends.