Saru-numa no Kyodai Kappa (Giant Kappa of Ape Swamp)
The Ape King told her that the ape population had dropped by a lot over the years. This was almost the last group, and if it continued like this, the balance of the forest would be lost. So she volunteered to help find the root of the problem. Until she met a swamp where there were almost no monkeys. As she approached, a strange bubble suddenly appeared and a giant kappa appeared. That made her realize right away that the cause was actually caused by Kappa. So she negotiated with it and explained things. What happened if the kappa continued to eat like this, one day the forest would have no life and you would have no food. So the kappa understood and asked for only 797 monkeys a year, so the girl went back to talk to the Ape King. The king understood and agreed to the contract. And this is the story of the Giant Kappa of the Ape swamp.