Yuko is a child of Shikanosuke's biological mother and her second husband, thus she is Shikanosuke's half-sister. She hasn't been told about the family's history though. Yuko is 3 years younger than Shikanosuke. She is a childhood friend of Souta, Yui, and Kazuki and were together since elementary school. Yuko is the president of the Girls' Light Music Club and the leader of the second Second Literature Club band.
Yuko is very studious and enjoys playing horror games. She looks for every opportunity to criticize her brother and is very straightforward with her opinions. Yuko is also very protective of Yui, mostly from the hands of Souta. She doesn't actively seek out a boyfriend, insisting that she simply isn't interested.
Yuko picked up the bass after her brother's success in the Second Literature Club band. She was the one who introduced rock music to Souta.
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. Yuko then enforced a 2 meter restraining order on Souta to protect Yui.
When Yuko enrolled in Ohbi Academy, she invited Yui and Mami to join the Girls' Light Music Club. The Girls' Light Music Club was formed after the success of the original Second Literature Club band. The Girls' Light Music Club is more active than the Boys' Light Music Club and the best players of the Girls' Light Music Club were chosen to form the Second Literature Club band.
Yuko enrolled in Ohbi high school and joined the Second Literature Club band, following in her brother's footsteps. She also decided to play bass as well. Shikanosuke drove Yuko to school to attend the Ohbi Cultural Festival.
Kira Kira: Curtain Call
Chapter 1: Here Today, Go Tomorrow
Yuko wanted to see Souta being forced to dye his hair back to black. Shikanosuke dropped Yuko off at school on the morning of the Ohbi Cultural Festival. She was upset that he couldn't watch her perform. The Second Literature Club band performed exceptionally well and Yuko went to brag to Souta.
Chapter 2: I'm a Rock'n'Roller
Yuko suspected that Souta had formed a band and he revealed that he had formed Super Rock'n'Rollers. Akihiro tried to hit on Yuko but she shot him down immediately. Souta voiced his suspicion that Yuko might be lesbian but she quickly shot back saying that if that's true, she would've taken Yui for herself. When Souta found a spot at the local live house, Yuko explained that he needed to sell tickets. She suggested singing at the Taishou Restaurant to promote his band. The patrons didn't like Souta's singing and beaten him up. Yuko and Yui then approached him and Kazuki to buy some tickets from them.
That Summer, Yuko had a training camp for the Second Literature Club band at Shouki's family temple and demanded Mami to keep it a secret from Kazuki. Yuko noticed that Souta and Akihiro were referring to each other using endearing terms and assumed that they were gay. Yuko and Souta agreed to practice at different times but she teased Souta during zazen.
On the last day of their training camp, Yuko noticed that Yui was very bitter towards Souta and suspected that something had happened.
Chapter 4: One Night Stand
Yuko and Yui watched 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.
Yuko furthered her studies to college after she graduated.
Chapter 2: Don't Stop Dreaming
Yuko contacted Sarina for a part-time job for her and Yui. 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.
Chapter 4: We Are Always Rock Crazy
On the night before Happy Cycle Mania's 5th year anniversary, Yuko phoned Souta to meet him at the park. Yuko requested Souta to invite Yui to attend the event. She officially nullified the restraining order on him. Yuko explained that although his dream is to be the sun and shine upon everyone, he was singling Yui out from his light. Souta announced that his feelings for Yui had been growing and phoned Yui to invite her to the event.
The next day, Yuko saw Shikanosuke off then went to the live house with Yui.
Yuko uses a white colored Fender Precision Bass. It seems to look most similar to the American Special model.
- Yuko's band costume features the same hat that is present in her brother, Shikanosuke's band costume.