The story takes place in the underwater world. Shark gang boss Reno has two baby sons Frank and Lenny. Oscar, a small fish at the bottom of the society, is a staff member of the cleaning shop, responsible for cleaning the whale’s oral waste. One day, Frank was about to attack Oscar, not wanting the iron anchor dropped by the fishing boat on the sea to smash his head severely. After confirming that Frank was dead, Oscar decided to make good use of this good opportunity for misconduct, so he raised his arms and shouted that he was the "shark killer" who defeated the behemoth, but he never thought that bragging would come at a price. Oscar was praised to the sky by everyone as a hero to the extermination of Anliang, prestige and wealth followed one after another. "Shark Killer" and Lanny, who wants to be a vegetarian, became good friends and joined forces to create a live TV show on shark hunting, and the hero became a superstar again. This fabled lie eventually led to Reno's pursuit of Oscar all the way. In the process of Desperate End of the World, Oscar was also involved in a battle between the rivers and lakes.