Yua Yaiba is a highly skilled engineer and fighter in the series Kamen Rider Zero-One. As Kamen Rider Valkyrie, she serves as a member of A.I.M.S., an organization combating rogue Humagears and their creators. Intelligent, composed, and resourceful, Yua frequently finds herself caught between her professional duties and her personal sense of justice. Her character undergoes significant development, grappling with her loyalty to her superiors and her own moral convictions, making her a complex and pivotal figure in the story.