Saya

is the sheath spirit of the demon sword Sō'unga. He is the spirit who was supposed to guard Sō'unga in order to stop the sword from being drawn. He is a slacker and is said to be unreliable since he didn't hold Sō'unga as long as he was supposed to. Saya said in a meeting with Myōga and Tōtōsai after the death of Inu no Taishō that he would be able to seal the sword for about 700 years. However, he was only able to do so for 200 years. He often tells people that bad things will happen after they already have, cementing the belief that he cannot be trusted with anything important.