She is a 12-year old girl with short white hair and ruby eyes. She is often seen wearing the uniform of Renpu Girls' School.
Sayaka is a young genius Toji. She handles her duties with ease, but she has a hard time communicating with the people around her. Although seemingly stoic, her eagerness to accomplish something reflects in her emotions; among the things she feels bad about is failing to fulfill whatever mission is given to her.
Sayaka eventually began showing more of her true feelings, and also began to learn deciding for herself, with the help of Mai Yanase's friendly gestures.
Not much is known about Sayaka, aside from that she joined Renpu Girls' Academy, and becoming their ace at very young age.
Sayaka was present during the National Swordsmanship Tournament as one of the representatives of Renpu Girls' School. She met defeat in the hands of Kanami Etou after a relatively long exchange of blows from the representative of Minoseki Academy.
After the tournament, like the participants and spectators of the tournament, Sayaka was held within the premises of the Origami Mansion until she was brought to the headquarters of the Special Sword Administration Bureau. Here, she received private orders from the president of Renpu, Yukina Takatsu, to locate and retrieve Hiyori Juujou, a representative of Heijou Institute who attacked Yukari Origami, and Kanami Etou, who was accused as Hiyori's accomplice. Sayaka managed to locate the whereabouts of the two, but was eventually disarmed by the combined efforts of Kanami and Hiyori.
Sayaka returned to the headquarters of the Special Sword Administration Bureau empty-handed, incurring the wrath of President Takatsu, and she was held within the premises of Renpu for a prolonged period. Here, she was consoled by Mai Yanase, taking care of her wounds and giving a bag of cookies as a kind gesture.
Later, Sayaka was prepared by President Takatsu in a procedure that would inject a vial of noro into Sayaka's bloodstream in an experiment. However, the kindness of Kanami and Mai immediately made her realize the costs of such a procedure. In fear of losing herself in the experiment, Sayaka broke out of the campus and went into hiding within the nearby neighborhood. News broke of Sayaka's escape, and both Yume Tsubakuro of the Elite Guards and Mai went on a separate search for Sayaka's whereabouts. Both Mai and Sayaka would later fight Yume, with only President Takatsu's presence barely able to stop Yume's rampage. There, Sayaka would defy Yukina's words for the first time and she left with Mai.
With the guidance of Minosaki Academy's president Ema Hashima, Mai and Sayaka were taken by car to the whereabouts of Kanami and Hiyori, as well as Kaoru Mashiko and Ellen Kohagura of Osafune Girls' Academy, as they were welcomed into the anti-Origami organization called Mokusa.
Master Swordsmanship: As a representative Toji of her school and being considered genius by Renpu Girls' Academy President, she is very skilled in kenjutsu. Capable of pushing Hiyori, another skilled Toji. In manga she even hard-pressing Kanami, who is an extremely skilled kenjutsu, for a considerate amount of time before losing. She even keep up and outclass Yume, a genius Toji who is the Fourth Seat of Elite Guard, for a while.
- Swordsmanship Style: Onoha Itto-Ryu (小野派一刀流?) - A swordsmanship style whose foundation is on the technique of "cutting down and henceforth slaying an enemy head-on", also known as "kiriotoshi". Practitioners start by learning hitotsu-gachi, followed by kiriotoshi, and all other techniques would develop from these techniques. The style has a reputation for "beginning with a kiriotoshi and ending with a kiriotoshi".
Immense Strength: She processes great strength, capable of blocking a full-force strike coming from a Aradama which capable of destroy a part of the bridge with ease. Shen can even leap with a great distance without using any Toji's power.
Immense Speed: She processes great speed and swiftness, capable of pressing Hiyori who is one of the fastest Toji in her generation. She also capable of maintaining a form of Jin'i called infinite phase Jin'i, allow her to continously perform Jin'i without any interval.
- Infinite Phase Jin'i (無限の姿迅移 Mugen no Sugata Jin'i?): A unique type of Jin'i that constantly increases the user's speed as opposed to the instantaneous burst of speed performed by using a normal Jin'i. When used, the user creates rainbow-colored afterimages in its path.
Munen Musou (無念無想? lit., "thoughtless, mindless" or "free from mindless thoughts"): Enters a state where one's emotions are suppressed. In this state, the user's fighting skill and Toji abilities are performed more efficiently.
Okatana: Myoho Muramasa (妙法村正?) - An uchigatana made by the famous swordsmith Muramasa. Engraved along the blade are the characters for "Lotus Sutra" (妙法蓮華経), the name of a known Buddhist scripture.
- Because of the bizarre affection Sayaka receives from President Yukina Takatsu, part of the student body of Renpu distance themselves away from Sayaka. This was demonstrated by the interaction between Sayaka and the runner-up representative of Renpu in the Swordsmanship Tournament.