One of my first children's books, and a great favorite with children, Kap the Kappa, is about a Japanese river elf, a kappa, who is an authentic folk creature. Kappas have a wide face like a monkey, a hard shell on their backs, and webbed hands and feet like a frog. But the strangest thing about them is the concave bowl filled with water in the top of their heads. As long as the water is there, the kappa is happy and strong, but should it spill out while he plays on land, he becomes very weak and could even die.
In my book, I stayed true to the kappa's nature as a trickster, but made my own narrative about his adventure. One day when Kap is out swimming, he is caught by a fisherman and adopted into their family, disguised as a real little boy. Kap tries to be human, but he cannot resist playing tricks and is finally caught by the villagers as he is dancing on a roof by the light of the pearl white moon. Kap is heartbroken to realize that he is a kappa, and not a real little boy. He then sets off on the journey that adoptees, whether folk creatures or human, eventually make back to their source - in his case, to the riverbed. His kappa family hold a special party for him where everyone dances by the light of the pearl white moon. Kap is thrilled to be back, but he dreams of visiting his human family again.
Little kappa, prince of grace,
Shell of turtle, monkey face,
The river you will rule one day;
Until then just swim and play.
But outside the river bed
Guard the water in your head.
Should the water splash and flow,
From your body life will go.
Remember always what we’ve said ‑
Guard the water in your head.