Issei serves as a Buddhist monk and key operative within the Experts of Justice, working alongside members like Youshi and Taisou. He employs Taoist magic channeled through paper talismans, enabling effects such as voluntary shapeshifting, disorientation, and complex illusions. These abilities provide strategic combat support, creating advantages for his team rather than direct offense. Issei also wields a sword and demonstrates proficiency in mystical arts, frequently partnering with Youshi on missions.

His background connects him to classical Chinese literature, specifically designed as an expy of Gongsun Shen from Yokoyama Mitsuteru's adaptation of *Water Margin*. Issei's role emphasizes spiritual and tactical support, leveraging illusion mastery to create openings against adversaries like Big Fire.

During the defense of the airship Greta Garbo, Issei and Youshi confront the monstrous samurai Koenshaku after his infiltration. Their combined efforts fail against Koenshaku's near-invulnerability. Throttled by the foe, Youshi initiates the separation of the ship's sections to prevent Koenshaku reaching the bridge. Issei participates in this desperate action. The sequence concludes with the apparent demise of both characters. Subsequent wreckage investigation by Tetsugyu recovers only Youshi's broken staff, leaving Issei's fate unresolved but heavily implied as a casualty.