Sasaki has dark colored hair that extend to below her ears, thin eyebrows, and wears glasses.
Sasaki wears light colored vest over a light colored long sleeve shirt and a diagonal stripped tie. She also wears a dark colored skirt, with light colored socks, and light colored shoes. While visiting Iguchi in the hospital, Sasaki wore a longer skirt, dark colored socks, and dark colored shoes.
At the Occult Research Club's room, the club members where playing a game of Kokkuri, until the student council president comes and informs them that their room is being taken due to lack of activity report. Sasaki tells the clubs theory that the reason for the school's rugby field got closed is due to being haunted, but the student president debunks it, saying it was due to ticks. He then informs that Itadori is not even on the club and the club doesn't have minimum required members. Sasaki and Iguchi then go with Itadori to sort things out with the Takagi-sensei, who changed his club activity. After sorting things out with Takagi-sensei, Itadori told Sasaki and Iguchi, that he liked the club and wanted to stay, to which they blushingly agree.
Later that night, Sasaki and Iguchi sneaked into school and while in the Occult Research Club room, they try to unseal the cursed charm they found. As they succeed, they are surprised it was a human-looking finger, but in that moment they got attacked by curses. As they ran, they got separated and when they reunited, Iguchi had a curse attached to his head. When Itadori and Megumi reached them, Sasaki and Iguchi were already unconscious and the curse was attempting to eat them, but Itadori saved them.
On the next day, Sasaki was at the hospital watching over the injured Iguchi and blaming herself for what happened. Itadori then insists that he is to blame for finding the charm and that people capable of healing Iguchi will come tomorrow.
As an ordinary human, Sasaki doesn't posses any additional abilities.
- Sasaki's name contains the kanji for "help, aid" (佐 sa?) and "tree" (木 ki?).
- Sasaki ranked 52nd place in the manga's 1st Character Popularity Poll with 106 votes.