A story of overfishing to raise children's environmental awareness. Includes craft activities at the end.

Izumi and his son live in a fishing village, where Izumi catches golden walleye. After a storm he discovers a cove full of such fish. Word spreads, and overfishing damages the seabed, impacting biodiversity. Izumi then sets out to clean up the cove. One day, his son notices the flora and fauna are back. This picture book raises children's awareness of environmental issues, especially overexploitation of the seabed, and the preservation of nature.
Inclues DIY activities at the end of the book with instructions to create koinobori (traditional carp-shaped windsocks).