Son of the woman Tsubasa's father is dating, Kazuma is a member of an indie-rock band named "Yin & Yang" along with minor characters Martin, Joker, Ushio, and Atsuya. His bleached hair and skull jewelry initially make Tsubasa suspicious of him. Despite this, he supports his mother's relationship with Tsubasa's father, hoping for a little sister and his mother's happiness. However, he mistakenly assumes Tsubasa is an elementary school student due to her short stature, which leads to a dramatic outburst from Tsubasa, who is actually one month older than him.
Kazuma's appearance, characterized by bleached hair and skull jewelry, often gives people the wrong impression. He is voiced by Akira Ishida. His most valued treasures are Tsubasa and his music. Gradually, he comes to realize that his feelings for Tsubasa go beyond brotherly affection. He also faces the harsh reality that his passion for music might eventually separate them.
