The Osa of Tono is the leader of the many Yokai in Tono. He often appears as an old man. His true form is that of a daitengu. When Ushio was being targeted by many yokai since they knew he was the son of Sumako Hizaki, Osa revealed himself to Ushio and exlained the situation and asked Ushio to learn why his mother was protecting Hakumen no Mono.
Osa is very wise, kind, and thinks very highly of Ushio, as well as having great faith in the boy.