Gai Mou is a part of the Seven Fire Dragons of Wei that were Generals who were fighting with Zhao's Three Great Heavens and Qin's Six Great Generals. At some point, Gai Mou along with Rei Ou sided with Earl Shi's conflict against Tai Ro Ji, Shou Sen, and Ba Tou, three other Fire Generals, with Tai Roji being personally responsible for the death of Earl Shi's younger sister. This resulted in the deaths of the opposing Fire Dragons. As a punishment, Gai Mou was incarcerated in an underground prison for 14 years along with his fellow Fire Dragons. (Source: Kingdom Wiki)