Hahaha. A friend told me about Kappa at a party a while back. Have you seen how to properly trap a Kappa? You dangle your ass over the water to lure one in and then your buddies spear it.
https://www.tofugu.com/japan/kappa/
Another creature from Japanese lore is the Tanuki. They are shape shifting raccoon/dogs that have magical expanding scrotums. Here is a scene from Pom Poko.
