Sayuki has long, straight black hair with square bangs and sharp black eyes. She wears a black jacket with gold buttons to cover her bandaged chest and stomach, a long black skirt that goes past her knees with black knee socks or tights and medium-heeled school shoes.
When using her stick, the tips of her hair changes to dark purple.
Sayuki has a cold and intimidating personality, but she also has a motherly and sweet personality. She was born with amazing skills with using a sword and spends her free time alone. Due to this upbringing, Sayuki is also calm and traditional.
When she was younger, she was kidnapped by a rival Yakuza clan. She used her stick to kill two men who were trying to attack her and Mrs. Ringa came by and put the murders on herself so her daughter didn't have to go to jail. Sayuki has felt guilt for her actions ever since.
Sayuki can make distant cuts with her katana by slinging her sword and thinking of what she wants to cut. When she uses her stick, blood flows from underneath her left thumbnail.
Sayuki can cut anything and make them hard, she shows an example of this when she sliced water from a fountain and smoke from a cigar and they became hardened solids. Later through training and practice, Sayuki learned to not only just Harden things she cuts but cause the whole object to turn into stone as well, as shown during her battle with Go, when Sayuki cuts and destroyed the Demon Blade Kuimaru, the blades hilt and Venus fly trap like tentacles began to petrify, moving up, the petrifaction started to affect Go's main body until she became a stone statue herself this ability needs a large amount of her Lifespan to use.
It can strengthen itself as said in Chapter 49.
- The "Sa" in her name means "sand", "aid", or "help" combined with "Yuki" meaning "happiness" or "snow".
- Her face has some similarities to Akuta Rintaro, a character from Mahou Shoujo of The End.
- Her appearance and stick are similar to Anai Miu, amother character from Mahou Shoujo of the End.
- She is the third main character to be killed in the manga. The first being Nijimi Anazawa and the second is Mikari Izumigamine.
- Her birthday is on April 14th.