Kougaiji
Kou, 紅孩児
Kougaiji is a youkai prince living in Houtou Castle with his father Gyumaoh and mother Ratsetsunyo. He's known for being one of the strong willed youkai, possessing a "heart of gold," excelling in martial arts, emitting fire projectiles, and having knowledge in youjutsu spells such as Engokuki (Demon of the flame prison). In Saiyuki, Kougaiji is an enemy to Genjou Sanzou and Sanzo Ikkou's party due to being forced by his stepmother Gyokumen Koushou to retrieve the 5 Sutras including the maten sutra from Genjou Sanzou. This is in order for him to obtain a reward promised by Gyokumen Koushou, who vowed to revive his mother Ratsetsunyo, who has been under a curse that turned her into stone in Houtou Castle. His strong devotion and kind nature earn him loyalty from his youkai followers and companions like Lirin, Dokugakuji, and Yaone, whom he saved from the clutches of Hyakuganmaoh.
In the sixth volume of the manga, Kou makes the near-fatal mistake of challenging Goku to a death match for the sutra. Both sides receive heavy injuries, as Goku removes his limiter for the fight, releasing the unstoppable Seiten Tasei. Dokugakuji manages to get the injured prince home, but is forced to hand him over to the care of Nii Jianyi and his scientists. Kou is not seen again until the eighth volume, when he reappears healthy but brainwashed.
Nii reveals that his mind was holding back his conviction, making him lack the power to defeat Goku.
