He is a youkai prince who lives in Houtou Castle together with his father Gyumaoh and mother Ratsetsunyo. Background He is one of the strong willed youkai who has the 039heart of gold039 excels in martial arts able to emit fire projectiles and knowledgeable in youjutsu including youkai summoning spells such as his famous Engokuki Demon of the flame prison. In Saiyuki Kougaiji is the enemy of Genjyo Sanzo and Sanzo Ikkou Genjyo Sanzo039s party as he is forced to work for his stepmother Gyokumen Koushou whom he detests to retrieve the 5 Sutras including the maten sutra from Genjo Sanzo. This is so that he can obtained a reward from Gyokumen Koushou who promised to revive his mother Ratsetsunyo who has been placed under a curse which turned her into stone in Houtou Castle. His strong devotion to his mother and kind nature earns him loyalty from his youkai followers and his companions who are willing to serve him in his task. This include his half sister Lirin whom he cares about very much his personal bodyguard and swordsman Dokugakuji who is more like an older brother to him and his personal alchemist called Yaone whom he saved from the clutches of the womaneating Hyakuganmaoh. Source: Saiyuki.wikia