Kaz has dark hair with lime green and pink highlights. It goes down to just below his ears, with pink on the underside of his hair. They have dark colored eyes in the same shade as their hair. They have three piercings on their left ear and two on their right ear. His favorite clothing item are handwarmers, which can be seen in almost all of his outfits.

Kaz presents a friendly and polite nature to others around him. They get along well with their classmates and make friends fairly easily, and are generally chill and fun to be around, matching the energy of their surroundings. However, this is only the persona he displays on the outside. He is easily distrustful of other people and believes that everyone only pretends to be nice in order to get through life. Therefore, complements and praise don't mean much to Kaz. He doesn't blame others for the way they act though, because he believes that presenting a fake personality is a part of growing up.

On the inside, Kaz is very judgemental and holds grudges easily. Since he feels that it is unacceptable to show this unpleasant side of him, he has a lot of unspoken anger and frustration, and these emotions are mainly expressed through his dance. Many say that they seem like a whole different person during dance practice, as they have a very intense air to them compared to their usual friendly personality.

Kaz always pushes himself to be better in all aspects of being an idol, leading to a habit of overworking. When he's tired, he mellows out more, being less sociable and friendly, but also more raw in terms of their feelings. In the end, they genuinely want to be able to express themselves to someone who understands how he sees the world, which is something that is being slowly fulfilled after meeing LALA.

Kazuki's name consists of the characters 和 (kazu - harmony, peace) and 希 (ki - hope). The character 希 is also the same character that is in LALA's name. The nickname LALA often uses for Kazuki is Kiki, a play on the Sanrio characters, Kiki & Lala.

Kaz grew up as the oldest child of their family, with constant pressure from his parents who were both successful people in the idol industry. From the very beginning, dance was Kaz's passion. They loved dancing, and therefore put a lot of hard work into it as a young child. Many people would praise him, saying he was very talented. However, his parents would always tell him that it wasn't talent that made people good at dancing, it was effort and hard work. And to them, Kaz was never working harder enough. No matter how much time Kaz put into practice, his parents would always discretely compare them to someone else, and each time that happened, Kaz would try and meet that new expectation. This is why he learned how to sing and perform on top of dancing in the first place. He believed that his parents would have these expectations for him because they loved him, and their parents had always seemed so kind and supportive. However, one day Kaz overheard their parents talking about how they thought Kaz would only be a decent idol because he was talented. They then had a big fight with their parents, and Kaz gradually realized that people only say nice words to appeal to others, and that this was a part of growing up in society.

As he grew up, Kaz distanced himself from his parents, as they began to directly criticize Kaz's choices and no longer covered up their feelings towards him. However, Kaz still deeply cared for their younger sister Hina and younger brother Yukio. They don't want their younger siblings to experience what they experienced, so he teaches them about not trusting others just because they said something, and how to be polite to others even when you're upset. They also teach them how to win arguements and fights, as well as other "skills" to protect themselves, so it's questionable whether or not Kaz is a good influence on them, but Hina and Yukio love him nonetheless. To them, Kaz is the best older sibling in the world. They are his self-proclaimed biggest fans.

Kaz originally aimed to be in a solo unit that specialized in choreography due to his distrust of others. However, in their first year at Yumenosaki, they met LALA. Their initial meeting was a terrible first impression on both sides, as they ended up having a dance battle in the school hallway during break which attracted a lot of attention, causing both to be called in by the the student council. As punishment, the student council president, Mao, forced them to form a temporary unit together, as they both didn't belong to a unit yet. They would be a unit for one month, and then they could decide what to do from there. Kaz and LALA started out as basically enemies, and even though Kaz would still retain a "friendly" face, they bickered and fought a lot. Over this one month though, they miraculously began to bond with each other, and decided to stay together as a unit for longer (although Kaz always told LALA that one day he would still pursue his career as a solo idol).

Now, Kaz and LALA are really close, even though they would never say it out loud. They are very comfortable around each other, and LALA is the only one Kaz feels more open towards. LALA is the only person Kaz complains and rants to, and the only person they can be blunt with, almost rude if perceived by an outside perspective. Because of LALA, Kaz has become a little more trusting of others.