The hoyau kamui is a god in Ainu lore, known as the master of lakes. It appears as a giant winged serpent with a stout and cylindrical torso, a pointed snout and a narrow head and tail. They have a terrible stench, as just approaching it can make one's skin fester and burst into flames. It hates the cold and thrives in warm temperatures.
"A snake god said to be the master of the lake in Ainu lore. It is also known as Sakusomoaipu, "He who is not to be spoken of in the summer". It has a thin head and tail, a fat body, wings on its back, a sharp nose, and red lining around the eyes and mouth. Its lake habitat gives off a foul smell; anyone who comes near will experience swelling of the body and hair loss."
—Devil Survivor 2 compendium
Hoyau Kamui appears as the strongest member of the Snake race. In Record Breaker, it is now second-strongest, with Kohryu taking its place as strongest.