Gaishi is a friend of Kantai. After the rebellion in Kei, Gaishi becomes part of the five-man squad in charge of defending the Forbidden Gate. Before Youko Nakajima was enthroned, he was in the Baku Provincial Guard.

When Risai comes to Kei and barges through the Forbidden Gate in order to beseech the ruler of Kei for help finding the missing Taiki, Gaishi appears at the gate to stop the guards from killing Risai, whom the guards believe is a dangerous intruder.

(Source: wikia)