She set out with Tatsumi and Ieyasu to earn money for their village. On the way, they were attacked by night bandits and got separated. Sayo managed to stay with Ieyasu while Tatsumi was separated from them. She and Ieyasu were then invited by Aria to her mansion, and she provided them with a meal that was drugged, making them lose consciousness. Sayo was then tortured to death, although she didn't submit to Aria and her family even until the moment of her death. Tatsumi personally slays Aria after he is told the truth about Aria and her sadistic family. There is a chance that Tatsumi was in love with her, as the illusion that Zank showed revealed her to be the most important person in the world to him.

Sayo was seen carrying a bow and a stack of arrows. She seemed to have good combat abilities and presumably was a well-trained archer, as Tatsumi stated that both she and Ieyasu were strong.