Kusuriuri

A mysterious wandering man with a vast knowledge of the supernatural and is mystical in appearance. He carries around a large wooden box filled with medicine and holy tools. Among them is an enchanted sword that is used to slay the mononoke. To use the sword the Medicine Seller must find the Katachi shape Makoto truth and Kotowari reasoning of the mononoke he wishes to exorcise. Once the sword has been unsheathed he transforms into a demonlike creature. While his origins are unknown it is clear that the Medicine Seller is not human or at least not entirely human he has elflike ears and pointy canine teeth. Even in the timeskip Bakeneko arc the Medicine Seller still appears as the same handsome youth from the previous arcs the only differences in his appearance from previous arcs is he now wears small round red stud earrings and a ring on his index finger. It was revealed in the Umibozu episode when the ayakashi asked the passengers fears the Medicine Seller calmly answers he is afraid that there is no form truth or reason at the edge of the world thus no longer having a reason to exist. Source: Wikipedia