Kentaro was from a rich family, but his family was murdered by thieves from Velice, he then vowed revenge. He met Seventh along the way and agreed to be trained in a demon realm. He met his partner Resharo, and both manage to take a spirit from the demon realm, he took "Wrym" as his spirit and can revert to a more powerful form of Wrym.
Unlike Resharo, Kentaro is a blabbermouth, he always says whats on his mind and doesn't care whom he hurt but he's also caring for his partner. He and Resharo was tasked to travel to Blacktorn, along the way, they learned Rapture has emerged from his sealing.