Shiori is a girl with a short stature, standing at fewer centimeters than Kanna. She has ashy-black hair tied in a side ponytail with two chopsticks. She wears frameless glasses.
Shiori is often seen wearing her school uniform: a dark blue dress, with wide shoulder straps, four buttons on the chest area, a slim belt around her waist and a knee-long skirt under it as well as a black cardigan.
Under the dress, she wears a white plain, long-sleeved shirt. Her ribbon is red.
Shiori is a member of the badminton club. She is a soft-spoken knowledgeable and resourceful girl, with a serious, cool personality. However, it is shown that while she is quiet and often mistaken as distant, she is actually extremely shy. As such, this shyness causes her to be unable to speak her thoughts and feelings. She also presents a modest attitude, and estimates her abilities with a lack of conceit.
She is first seen watching Tamako, Midori, and Kanna walking together on the day before school rosters are put up in her second year of high school. On the way home, she encounters the royal bird Dera who was attempting to fly but resulted in falling to the ground. Shiori catches him with her badminton, though her arms are unable to sustain his weight and he lands regardless, with her musing that he had been heavier than she thought. Dera is clearly struck with love, however Shiori remains expressionless.
The following day, Shiori reads the class roster and discovers she is placed in the same classroom as Tamako and Kanna, Class A. Tamako, upon acknowledging this, catches sight of Shiori and attempts to greet her but is seemingly ignored causing her to wonder if Shiori disliked her.
Later that afternoon, she has a confrontation with Dera once again, who she catches with a folder. Hearing him comment that it was destiny, she asks him how a bird such as himself was speaking. After introducing each other, she escorts him home. As a "humble abode of thanks", he offers a cup of tea and resorts to convincing her with Tamaya mochi shop's sakuramochi. Throughout her traveling through the marketplace, store owners are seen greeting her cheerfully in the assumption she is one of Tamako's friends.
Reaching the mochi shop, she discovers it is Tamako's family's and is offered to stay, at which she declines. However, Tamako stops her and requests she try one of their sakuramochi. She does, and is later shown waiting in the living room at the table. Glancing around the room, she smiles a small smile. After hesitantly trying out the sakuramochi, she is about to return home when she receives a phone call from her mother, who informs her daughter she will be coming home late at which Tamako insists Shiori to stay for dinner. Anko behaves friendly to her as well, offering her pudding, to which Shiori seems surprised.
Shiori cooks a meal for Tamako's family with Anko, a meal that is praised. Tamako's father, Mamedai, apologizes to Shiori for cooking despite being a guest. Shiori's father calls her, and she is informed the bath at home isn't working. Subsequently, she comes along with Tamako to the public bath house.
Anko compliments Shiori's hair, while Tamako does so to her skin. Shy, Shiori does not respond. Afterwards, Tamako requests that she sleep over, which Anko concurs with, though she declines. Dera escorts her to the north gate train station, and she leaves without hearing Dera expressing his wish to walk with her alongside the cherry blossom-lined streets once more.
The next morning in class, Tamako approaches Shiori and greets her. However, Shiori reacts with a restrained attitude, only nodding slightly, and leaves the classroom without uttering a word. Shiori practices thanking Tamako for yesterday in the bathroom mirror at school with frustration. Upon seeing Midori enter the bathroom, Shiori quickly leaves. In class, Shiori glances at Tamako but looks away guiltily when Tamako waves. She attempts to thank Tamako once again at gym, but Tamako is distracted by Dera who visited the school, much to her disappointment.
On her way home, she and Dera encounter each other once again and she requests that he tell Tamako her gratitude for the other day. Dera, on the other hand, believes it would be better if she tells Tamako herself. At that moment, her homeroom teacher is shown to need assistance to Tamako's house for a conference, giving her a reason to return to the market place. The market shop owners are seen to recognize Shiori, and behave friendly to the teacher just as they had to Shiori the day before.
While Tamako's father and teacher speak to each other, Tamako apologizes for Dera and they later go to a coffee shop, where Shiori is finally able to express her gratitude to Tamako. She tells Tamako she had fun, at which Tamako agrees. They share a laugh and Tamako pours milk into Shiori's bitter coffee for her.
She disputes the mystery of the ghosts in Usagiyama District for the shop owners to relieve their worries with logical deducation later on.
One day, Shiori finds Midori is venting her frustrations in the bathroom. Realizing Shiori was there, Midori quickly left. Shiori later tells Tamako what happened as a contribution to the situation in a phone call, indicating they have established a closer friendship.
She is seen in the beginning of the Tamako Love Story movie playing badminton in the background. She accompanies Tamako and her friends on their way home home where they discuss their future planning survey forms, as this is their final year at school, confirming they have all established a more intimate friendship. Shiori is considering to attend a university overseas to study English literature, but muses whether or not she could take such a lifestyle seriously. She does decide to, however, and plans to stay at a home with an English family, believing that it's best to try out opportunities. She is later seen in the ending credits alongside Midori and Kanna.
Shiori is shown to play badminton well, and seems to deem it a favorite hobby as she is seen often carrying her racket by hand. She also appears skilled in cooking, demonstrated when she had prepared a "fancy" dinner, according to Tamako, composing of Italian carbonara with a side of vegetable soup for the latter's family. After graduating, she consults the thought of studying English literature overseas, indicating she is equipped in language enough to go overseas to study such a subject.
- Dera Mochimazzi: Dera has expressed romantic interest in her ever since he first saw her. Shiori doesn't show much of a reaction to this, however, and informs him that she did not play badminton because she liked feathers. Nevertheless, she is thankful to him for his assistance in forming her friendship with Tamako.
- Tamako Kitashirakawa: Initially behaving reserved towards Tamako, though admiring her and her friendship with Kanna and Midori from afar, Shiori later establishes an official friendship with her. Due to family situations, Shiori had ended up staying for dinner and cooking for Tamako's family to joining Tamako to the baths in one afternoon. After overcoming her shyness to convey her gratitude properly, they become friends and she is slowly seen more accompanying Tamako. In her third year, she is seen accompanying Tamako and her friends on the way home.
- (To Dera) "I'm . . . not lovely at all."
- (Referring to Tamako, Midori, and Kanna) "You know, I was always watching you three in the gym. You always look like you're having so much fun. I was so happy that we were put in the same class."
- She is blood type A.