Spoiler

Originally a human disciple of Genshitenson's named Ou Eki, he was traded to Tsuuten Kyoushu for Youzen in order to maintain relations between Kingo and Konron. Because Kingou does not allow humans, he was locked away until Dakki appeared and split his soul into three and giving them yokai bodies. He has the paopei Kousuijin which causes acid rain, and the paopei dani, an animal type peopei like Youzen's Koutenken, but in the form of tiny ticks that secretly latch onto sennin and drain their energy as if they were constantly using a peopei.

(Source : Wikipedia)