Raipiraki

Raipiraki was an incredibly skilled archer who participated in the Toushin Tournament and became a semi-finalist before being defeated by Custom. His partner was Amiga. Little did anyone know (prior to the quarter-finals), but Raipiraki was also a member of the elusive weredragon species, and used his alternate form, a coppery-scaled humanoid dragon, during both those final rounds. As a dragon, he was immune to any weapon besides a Dragon Slayer, but thanks to Raipiraki revealing his true self in the previous round, Poe was able to inform Custom of the complication, allowing Custom to acquire a Dragon Slayer in time.

Trivia

 * Raipiraki is the only Toushin Tournament opponent who does not speak to Custom prior to or even during their duel, and his partner. Amiga, does not discuss him in detail, making him something of an enigma.