Kumiko loves monochrome. She has a deep affection for black and white, which dominates her everyday clothing and personal belongings. Surprisingly, her underwear is vivid pink—but this is closely tied to her love for black and white. Her obsession stems from her passion for the piano. Having studied piano since childhood, she grew up alongside a grand piano at her family home. Her mother once said, "Maybe you'll become a pianist someday," but Kumiko never really cared about playing music. Instead, she was drawn to the piano's appearance, its nature, and the feel of the keys. To her, the piano was an irreplaceable, never-betraying presence. However, one day during elementary school, while friends chatted about marrying someone they loved, Kumiko confessed, "I love the piano," only to be laughed at with, "You can't marry a piano!" For the first time, she felt betrayed by the piano. After that, she quit lessons and stopped sleeping beneath it. She began pursuing relationships with ordinary people. Though her first love remains unforgettable, she still finds herself attracted to black and white objects. Eventually, her ordinary romance led to ordinary sex, and Kumiko grew fond of the penis—perhaps influenced by its appearance and nature. Recently separated from her boyfriend, she agreed to participate in an AV shoot, driven purely by the desire to touch a penis. So far, she hasn't been betrayed again.