|“||All high school girls like cute stuff, so there shouldn't be any problem there!||”|
Yui Kiriyama (桐山 唯, Kiriyama Yui) is a classmate of Aoki and a member of the Student Cultural Society. Despite her small build, she has a black belt in karate and has won many tournaments from her years in middle school. Yui has an affinity for cute things and her room is full of dolls and adorable accents. In addition, though she tries to keep it a secret, Yui suffers from androphobia.
Yui has a spirited personality and expresses her emotions very clearly and honestly. While usually shown to be sweet and kind-hearted, Yui tends to lose her cool when around Aoki, whose perverted antics tries her patience. She is also rather self-conscious about her body in general and especially dislikes when others point out her underdevelopedness. Though gentle by nature, Yui is also a proud practitioner of karate and is always ready to put her skills to good use, not afraid to get violent if she must.
Yui has also proven to be rather naive and a bit idealistic. Having long had an aversion to men, Yui has little to no understanding of how romantic relationships work, instead having a rather romanticized idea of it. She is often quick to trust her heart's instinct without really thinking things through, which has proven her undoing several times. When given the power of Dream Perception along with the rest of the Cultural Club by Heartseed, Yui chose to use the power to help those in need.
In Yume Random, Yui aspires to become a police officer and plans on taking Art courses in her 3rd year. Yui later decides to attend a university and learn foreign languages.
Throughout the series, Yui struggles to overcome her androphobia; a fear of men. Her androphobia was developed after she was nearly raped in junior high.
Though more subtle, another one of Yui's great challenges is learning to rely on her own strength. Many times throughout the series, Yui has to lean on her friends for support during challenging times, often choosing to avoid her problems altogether if she is alone. As the story goes on, Yui progressively gains strength, not just of body, but of constitution as well.
Yui is a young woman of small stature and has green eyes. Her long, strawberry-blonde hair is parted by hair clips and Yui will often wear her uniform's sweater around her waist. She is frequently described as looking much younger than her actual age. She also wears an A-Cup bra.
Yui originally wanted to join a "Fancy club" due to her fascination with cute things; however, the club did not have enough interested members. As a result, the school placed her in the Student Cultural Society.
In junior high, Yui was extremely skilled in karate and regularly defeated her rival and friend, Mihashi along with the boys of her dojo with ease. As a result, Yui was very overconfident about her strength and felt superior to any man. However, during Yui's third year of junior high, a man attempted to sexually assault her and she barely managed to escape, even with her martial art expertise. This traumatic event, compounded by her previous confidence, caused Yui to develop androphobia and lose sight of her ambitions.
- Anzu Kiriyama: Yui's younger sister. Anzu has a habit of misreading the situation and drawing wild conclusions, such as in Kako Random when she assumed either Yui or Inaba was the mother of a Time Regressed Iori, and Taichi was the father. Anzu does not seem to be aware of Yui's androphobia.
- Yaegashi Taichi: A male StuCS club member. After he helps Yui take her first step towards overcoming her androphobia, Yui develops a strong bond with Taichi, considering him her most trusted male friend. Though she greatly admires his kindness, Yui has clarified that their relationship is platonic. In Yume Random, Yui and Taichi team up, mutually believing they should use Dream Perception to help others. Their endeavors ranged from helping solve trivial problems like finding a lost phone strap to clearing up a false criminal accusation. Taichi later helps Yui learn some pro wrestling moves which aid her in her match against Mihashi.
- Nagase Iori: The President of the StuCS club. After overcoming the many trials of the phenomenons together, Yui and Iori form a close friendship. Yui is often the first person to comfort Iori if she is troubled, and vice-versa.
- Inaba Himeko: The Vice President of the StuCS club. Inaba was the first friend Yui shared her fear of men with. The two are quite close and Yui even helped Inaba prepare chocolates for Valentine's Day.
- Aoki Yoshifumi: A male classmate and fellow StuCS club member. Yui has consistently turned down Aoki's many love confessions, though she gradually warms up to him over the course of the series. Yui is always appalled by Aoki's perverted antics, but can never bring herself to hate Aoki himself. It is later thanks to Aoki's love and dedication that Yui eventually overcomes her androphobia. During the events of Yume Random, Yui and Aoki's conflicting morals put a strain on their relationship but they later make up. She then confesses to Aoki and the two begin dating. In Precious Time, Yui teams up with Aoki for the Couples Battle Royale.
- Kurihara Yukina: Yui's friend and classmate. Yui and Kurihara are very close, and the latter likes to consider herself as Yui's older sister. In Step Time, Kurihara sets up a triple date for Yui, hoping to help improve Yui's relationship with Aoki.
- Uwa Chihiro: A close friend and fellow practitioner of karate at Yui's dojo that she forced to join the StuCS. Chihiro seems to be quite close with Yui and he knows her well enough to understand her weaknesses, which he is more than willing to exploit. Kiriyama told Aoki that Chihiro is the type of guy she likes only based on appearance but he is not the one she can go out with. During the sports festival's final event, he insincerely confesses to Yui to throw her off, allowing his team to win.
- Oosawa Misaki: Yui's friend and classmate. During the autumn of their first year, Misaki confessed to having a crush on Yui and asked her out on a date. Yui did express interest in dating a girl, not understanding why everyone thought it would be wrong. Yui agrees to the date, but later turns down Misaki, realizing that such a relationship was not what she thought it would be and the two become friends instead. Yui thought that Misaki's boyish look was cute.
- Fujishima Maiko: Fujishima rarely interacts with Yui directly, but the two seem to be on good terms. In Clip Time, Fujishima gave Yui a push to go on a date with Oosawa, and it is later revealed that Fujishima was the one who gave Oosawa the courage to write a love letter to Yui.
- Kaidou : A friend Yui had lunch with as seen in episode 2.
- Mihashi Chinatsu: Yui's old friend and karate rival. In junior high, Yui would regularly defeat Mihashi and they would later promise to one day fight each other in the finals of the national tournament. Mihashi does not approve of Kiriyama joining the StuCS because she feels that it has no purpose. Becoming close friends after Kako Random, Yui occassionally calls Mihashi and consults with her about her problems. In Precious Time, Mihashi visits Yui's town and participates in the Couples Battle Royale with Anzu. Yui and Mihashi later decide to have a special karate match for the other students to watch and Yui emerges victorious, defeating Mihashi with her "Shining High Kick." She learned the technique from a pro wrestling DVD recommended to her by Taichi, proving that her time spent with the StuCS was not a waste.
- Yaegashi Rina: Yui met Rina when the StuCS visted Taichi's home. When it was finally Yui's turn to talk to Rina alone in the living room, Yui could not control herself and started hugging and touching Rina all over because she is cute. In the end, Rina could not ask any questions and only put down that Yui is scary in her notebook.
- Yui has only been shown wearing her uniform properly once in the entire series: in Episode 9 of the anime.