Yua Yaiba is a technical adviser of A.I.M.S. who transforms into Kamen Rider Valkyrie. She temporarily was the Fighting Jackal Raider before her defection. Yaiba is an extremely professional and by-the-book agent, remaining levelheaded even in the most dangerous situations. However, despite this cold and often stoic demeanor, Yaiba does possess humanity and sympathy for others as she was worried and cried for Fuwa after he was put comatose by Horobi. She is close friends with Fuwa Isamu.