Sayo Kadoya (A New Decade)

Sayo Kadoya (門矢 小夜) is Tsukasa's younger sister. She is a pianist and is the planner of Tsukasa's and Natsumi's wedding.

History
Sometime after the Kamen Rider War, Sayo joined Tsukasa and Natsumi in the Hikari Family Photo Studio. She is the person who watches over it while Tsukasa and Natsumi are off on missions in the other world, replacing Natsumi's deceased grandfather from the role in Decade proper.

Portrayal
Sayo Kadoya is portrayed by Moe Arai (荒井 萌).