Kosaten is a mysterious Oni who travels the world in search of barter. They're a trader, but they accept no coin, only trading items perceived to be of equal worth to those they sell.
Nobody knows where Kosaten comes from, or where Kosaten goes when the deal has been struck. Occasionally, Kosaten has been known to provide shelter and safety to travelers they meet on the road, but nobody knows why Kosaten sometimes chooses to do this, and other times does not.