Sei Kai was deemed the Commander-in-Chief of an army of over 50,000 during the Battle of Kankoku Pass. He and his army pushed the walls of Kankoku gate alongside the Wei army, with poison archers and poison catapults as they lay siege to the Kankoku wall. The army specialized in poison weaponry since Sei Kai was a poison specialist. The Kan Ki and Chou Tou armies descended the Kankoku Wall and sent out units disguised as Wei soldiers to attack the Han army's HQ where Sei Kai was located.
The HQ force which was led by HQ defense chief Na Kon who tried to stop the momentum and defend Sei Kai but the forces broke through and successfully pushed their way into the HQ, Sei Kai's Black Arrow Poison Unit tried to stop them but failed and Chou Tou managed to slay Sei Kai but died afterwards because of Sei Kai's poison the day before, resulting in both the Sekai army's and the Chou Tou Army's defunct. Chou In replaced Sei Kai as stand-in-commander of the remaining Han army.
