Mermaid princess Era is revered by her fish friends in the ocean. Unfortunately, the lives of her fish subjects are cut short when they are caught by human fishers, and when her friend Bonito is caught one day, Era decides to go ashore to pay her tributes despite warnings from others.

Transforming herself into a human, Era enters the fish restaurant that bought her friend and orders his dead, seared body. After praying for him and the rest of her friends who had been captured, Era is about to leave when one of the customers in the restaurant tells her that Bonito will not be able to enter Heaven. Wanting to properly send him off, Era decides to take a little bite—only to instantly develop an addiction to seafood.

A tale of a cannibal mermaid now unable to stop thinking about how her citizens would taste, Ningyohime no Gomen ne Gohan follows Era's desperate attempts to hide her urges and her dark secret.