Shamoto runs a small tropical fish shop. Murata also runs a tropical fish shop, Shamoto establishes a bond of friendship with him rather quickly. Mitsuko even begins working for Murata and living at his house. What Shamoto is unaware of is that Murata's friendly face disguises his many deep dark secrets. He sells cheap fish at high prices, and if anyone refuses to go along with his moneymaking schemes, they are murdered and disposed of by Murata and his wife in grisly ways. By the time Shamoto realizes that Murata is insane and a serial killer with a body count of fifty, he finds himself powerless to do anything about it.