based on the creature of Japanese Shinto lure. in my universe they originated on the planet TuRR and have a connection to the native ferret people . the oni take the form of ferret girl revealing themselves at their wedding, the transformation will look like a Japanese oni mask , all onis could be considered female and depend on a symbiosis relationship with the ferret people to reproduce. the shape is that of an east Asian dragon with porcupine quills made of a crystal like material. both species belong to a group of mammal like amphibians that evolved on TuRR,