Born and raised in the Netherlands, Yuki had been obsessed with singing contests on TV from a young age. Her favourite activities were watching a talent show called Great Voices and practising her singing in the bathroom using a hairbrush as a microphone, pretending to be a singer on the Great Voices stage. She would often use any opportunity to provide her parents with improvised performances. They were delightful, but a five year old usually does not have the best musical training. For this reason, Yuki's parents decided to sign her up for singing lessons, which Yuki enthusiastically accepted.

At age six she started singing lessons in a group. Chasing her dream of appearing on an episode of Great Voices Junior, Yuki took the singing lessons very seriously and she used all her free time to practise, hoping that her parents would sign her up. All the practice paid off, and after five years of dedicated singing, her parents decided she was ready and filled in the application form. When Yuki was 12 years old, her application for Great Voices Junior was accepted and she entered the qualifying round. Yuki was ecstatic to finally see the judges in real life, to get a feel of what it's really like to stand on that Great stage. As she walked onto the podium, the spotlights on her, she knew that this is what she was made for. This would be her destiny, and she must win. Filled with determination, she sang the judges' socks off and she passed the qualifying rounds with flying colours. Now that she got a taste of what it was like, she knew that she couldn't stop there. She had to get to the finals, at least. Almost unable to contain her excitement after the qualifying round, she practised even harder and sung even more.

When the big day of the first round finally arrived, Yuki ran to the studio. She was very curious to know what it would be like to see the audience, hear the big applause. She couldn't wait to show the world what she could do. The stylists did her hair and make-up, and she got into her outfit. Looking into the mirror, Yuki didn't feel nervous at all. She has been preparing for this moment her whole life, and she finally reached it. As she heard the announcer start the show, she laughed. Yuki listened the other kids sing and it fuelled her excitement even more. The stagehands led her to the stage. This would be the debut to her singing career, the start of the life of her dreams. Yuki set one foot on the stairs and peeked at the audience. Suddenly she got nervous. That's a lot of people. But this is her dream, this is her chance. Yuki closed her eyes and smiled, she's ready. She set another foot on the stairs. Or at least, that's what she thought. Yuki missed the second step of the stairs by approximately 10 cm, unable to keep balance with her eyes still closed, she fell forward and hit her head. Yuki was brought to the emergency room with an injured nose and a concussion, and was excluded from the Great Voices Junior season, as she was still recovering while the episodes were being streamed.

Yuki and her parents attempted to sign her up for the next few seasons of Great Voices Junior, but she was rejected because she was already registered as a candidate for a previous season. Age 13, Yuki joined her high school's music club and formed a band with members of the club. Being a member of a small school band is a pretty big step down from being a candidate in Great Voices, but it was all that Yuki had. The bond between band members strengthened every practice session and Yuki found peace with her new friends that shared her passion for music. 

As the voice provider of Tsugi is my IRL little sister, please do not make content shipping or pairing Yuu or Yuki with Tsugi. It's just weird man. Don't do it.