Yuko Imai, a serious and conscientious former singer, saw her career abruptly end due to a devastating vocal cord infection that destroyed her voice. This forced her transition into artist management within the music industry. While working in this capacity, she discovered Kaori Shiina on the street, recognized her potential, and dedicated herself to training Kaori as a professional singer.

Yuko maintains a dual relationship with Kaori, serving as both her manager and romantic partner. She possesses intimate knowledge of Kaori's hermaphroditism and actively conceals this secret to shield Kaori's career from public scrutiny. This protectiveness stems partly from Yuko's own traumatic past experiences within the industry, where she and fellow singer Saki Midorisawa endured systematic sexual abuse by record officials. The two initially supported each other through this abuse, but their partnership fractured when Yuko departed without explanation due to her vocal injury, leaving Saki embittered.

When Saki discovers Kaori's secret and attempts blackmail to force a relationship, Yuko intervenes to protect Kaori. She reveals the truth about her shared abusive past with Saki and the medical reason for her abrupt departure. Demonstrating her commitment, Yuko participates in and wins a sexual challenge orchestrated by Saki to secure Kaori's freedom and ensure the secret remains kept. Despite this resolution, Saki subsequently joins Yuko and Kaori at their office, signaling ongoing tension.

Yuko's background of industry exploitation directly informs her protective approach toward Kaori, blending professional dedication with personal loyalty forged through their shared vulnerability.