Thank you! I find it hard to say where ideas come from so this will be a bit fragmented - When designing anything from folklore, I try to make it look unfamiliar while keeping the essence of the thing - with this Kappa it was taking the idea of the Kappa’s head as a container for water to an extreme, extending it to the entire Kappa - a living hollow container. I tried to make the water look stagnant to give him a feeling of age and eeriness. I like to make the body mass of folklore creatures out of unidentified translucent jelly or glass like substance and combine it with a layer of more natural bumpy texture - I hope this gives them a feeling of being part of our world but otherworldly. I wanted this Kappa to look like he had accumulated lots of algae and weed on his surface from living in the river, but also to make it ambiguous if the green is just a layer of slime or if it’s growing from his “skin”. Hope that’s a good answer!