Qiu Yongsi is a scholar from Xihu who showed up in Chang'an chasing rumors about the Black Jiao—supposedly a creature that had transformed into a yao king. He got pulled into the Exorcism Department after receiving a mysterious invitation, and basically became the team's walking encyclopedia on obscure weapons and forgotten lore. His knowledge of lost techniques and rare armaments made him invaluable to the group's work.
Content compiled by AnimeList.moe from publicly available sources.
