Yakuzou is a medicine man who travels the lands to wherever his talent and medicine are needed. His progress is stopped when a rockslide blocks the path to a town where they urgently need his expertise. He asks the player for a Putrid Gastric Juice so that he may cut his way through the rock, since it supposedly has the properties to cut through steel. Now that he has the Putrid Gastric Juice he will continue on his journey to heal the Youkai who need his medicine.
Yakuzou is indebted to the player for his help in acquiring the Putrid Gastric Juice needed in passing through an avalanche to a troubled town. He returns this kindness by providing the player with the eye drops he needs for Akugorou, Kosanta, and Matashige itchy eyes for free.