Agarizame dwells in the water surrounding the island on which Neko Majin Mike and Kojiro live. Thirty-one years before the events of Nekomajin, Neko Majin Mike warned Agarizame not to cause trouble. But while Neko Majin Mike was asleep during the following 31 years, Agarizame eats all the cows and farming of the island, and all the people who try to chase him away are devoured as well. One day, he appears in a field about to kill a cow, but the cow suddenly turns into Neko Majin Mike. Agarizame lies that he was not about to kill the cow. However, Mike did not believe him due Kojiro having already told Neko Majin what Agarizame did. Agarizame is quickly killed by an energy wave from Neko Majin Mike, and Mike later assumes the monster's shape in order to help Kojiro gain confidence in.