Yuuki's dorm-mate and best friend since middle school. Yuuki often refers to her as Yori. Sayori seems to be one of the few girls who are not interested in the Night Class. She finds them a bit scary and stated that she would prefer someone from the day class. Sayori is also very observant. She notices a lot of things that happen to Yuuki, especially when she gets hurt or is very depressed.
Sayori finds out that Yuuki is a vampire after Hanabusa protected her from a Level D vampire, who served Rido. Despite that fact, Sayori still accepts Yuki and appeared to be more worried over the fact that she would lose her best friend. Because of the recent events at Cross Academy, she is taken to a safe place by Aidou on Kaname's orders. After the attack is over, she defends Hanabusa when the other day's class girls are afraid of him. Sayori is allowed to keep her memories and is one of the few day class students that know about vampires' existence. During the one-year time skip, she now has a deeper friendship with Zero Kiryuu (even to be thought of as Zero's girlfriend by Kaito).
Kaito helps Sayori to sneak into a vampire ball in chapter 53, and Zero freaks when she appears at the ball. Kaito and Zero promise to keep an eye on her while she goes to find Yuuki. Sayori was surprised after seeing Yuuki in her vampire form. She is astonished at the change in her best friend. Yuuki, who was once the tiny day class student and the naive one, was now taller than Yori herself and was more mature.
It also later revealed that Sayori's father is a Councillor in the Vampire Hunters Association.
After the events of Vampire Knight, it is shown that Sayori and Hanabusa began a romantic relationship, which leads to marriage. They eventually had a child and then grandchildren later on. However, due to different life spans, Hanabusa tries to convince Sayori into turning her into a vampire. She refuses his request, saying that she would prefer to live her life as a human, and eventually dies due to old age. During her last meeting with Zero before her death, she joked that she had been waiting for an invitation to Yuuki and Zero's wedding. However, one year after Sayori's death, Zero and Yuuki became an official couple.
