Sayo is a captain of the Kurokumo Clan.

Sayo is a cunning and ruthless woman and clan leader. She has strong business sense, entrusted to carry out delivery of Nuovo Fabric to the Thumb , as well as producing income through 'protection' rackets that force Nest dwellers to pay a fee, else they face violent mutilation. Sayo is rather merciless, likely a mindset she adopted growing up in the Backstreets "covered in filth and blood". Though her policies are extreme, she understands her strength and decides to back away from fighting the lone Index messenger, knowing he would overpower her. However she still challenges formidable enemies to duel, such as the L'heure du Loup, to which she loses, and accepts the terms to go to the Library or face death.

Sayo has a medium voice with a sultry and smug tone.