To celebrate their graduation from university Kaori and her two friends visit Okinawa in southern Japan for a short vacation. At the vacation house, provided by Tadashi's uncle, a numbing stench awaits the girls, and can be traced to a horrendously deformed, legged fish that Kaori kills. More and more of these creatures appear and portend a horrific change for the animal life in the area. A phone call from Kaori's fiancé Tadashi in Tokyo quickly shows the scope of this epidemic, when he is also attacked by these mechanized fish. Kaori immediately sets out on an perilous voyage to find out what happened to Tadashi, helped by Shirakawa — a videographer in search of the truth behind all this...

The story centers on the growth and paths in life of Nikuko and Kikuko, a mother and daughter who lives on a boat.