Yui is a second year student of Ohbi Academy. She is a childhood friend of Yuko, Souta, and Kazuki and were together since elementary school and is a relative of Kazuki. Yui is a member of the Girls' Light Music Club and the second Second Literature Club band. She is a vocalist and guitarist and Souta, who is of the same role, considers her a big rival.
Souta awoken to his feelings for Yui in the middle of class. He rushed to her and kissed her which sent her into a terrible shock. Yui developed mild androphobia from that debacle. Yuko then enforced a 2 meter restraining order on Souta to protect Yui. Souta promised to make Yui fall in love with him to overcome her fear.
Yuko invited Yui to join the Girls' Light Music Club. They were chosen to form the Second Literature Club band.
Kira Kira: Curtain Call
Chapter 1: Here Today, Go Tomorrow
Souta phoned Yui after he left the live house. His senior Tanabe arrived to pick him up and Souta requested Yui to wait for him to call back. She stayed the night up waiting but after a few hours, she decided that he won't be calling back and slept. The following day, Yui was tired from lack of sleep.
Chapter 2: I'm a Rock'n'Roller
The night before Super Rock'n'Rollers' first live house performance, Souta phoned Yui to meet her at the park. Souta explained that his goal in forming a band is to be the sun and shine upon everyone. Yui became sad, explaining that the sun is lonely in the sky and that Souta had promised to be with her.
After Super Rock'n'Rollers' failed performance, Yui reprimanded Souta and Akihiro for fighting on stage.
On the Second Literature Club band's last training camp night, Yui invited Souta to a convenience store. She advised Souta to write about his feelings for his song's lyrics. Yui confessed her feelings for Souta. She explained that she had overcome her fear and demonstrated it by standing close to Souta. Souta kissed Yui which enraged her because she did not expect it.
Chapter 3: Chain Saw
After the band competition, Yui confronted Souta at school at night. She heard from Mami that Souta was going to quit school. Yui explained that she liked the original song that Souta played during the competition. She lent him a guitar and sang while he played. Yui then voiced her anger because he promised to be with her. Souta insisted on maintaining his desire to quit regardless.
Chapter 4: One Night Stand
Yuko and Yui were on the rooftop watching Souta as he ran from school. Yuko asked if Yui was okay with it and Yui explained that she could do nothing to change his mind. Yui yelled at him, calling him an idiot.
Yui became stronger after Souta left. She insisted on waiting for his return.
Chapter 2: Don't Stop Dreaming
Yuko and Yui met Sarina and requested for part-time jobs from her. Sarina gave them jobs at one of her companies.
Chapter 3: Let's Do It, The Music
Sarina, Yuko, and Yui were returning from an on-site job and they met Shouki. He revealed that Souta had reunited Super Rock'n'Rollers. Jutaro phoned Yui using Souta's cell phone and invited her to meet Souta. She saw Souta drunk and dancing around topless. She knocked him out and they went to Yashiro's place. Miru revealed to Yui that Souta had always been thinking of her. Mika suggested using suggestion on Souta. Yui whispered to Souta to always be with her. That night, Souta suddenly woke up and played his guitar. Yui followed him and they left the room.
Chapter 4: We Are Always Rock Crazy
Souta phoned Yui to invite her to attend Happy Cycle Mania's 5th year anniversary. He explained that he thought that he could only chase one dream at a time, and that he had chosen rock over Yui. Souta realized that he should chase after both dreams simultaneously and requested Yui to listen closely to his song.
Yui uses a white colored Gibson Melody Maker Special.