Kyoko Milchan works as an auditor and accountant for the Department of Security's Central Headquarters Special Services. Her role expands into operational support, logistics management, and intelligence gathering for the division. She strictly adheres to protocols and regulations, a stance that creates friction with field agent Daisuke Aurora due to his relaxed, rule-bending methods. This fundamental clash in professional conduct frequently causes her significant stress during their interactions.

She once harbored romantic feelings for Shun Aurora, Daisuke's older brother and head of the Special Services Division, but these feelings later shifted toward Daisuke over time, marking an aspect of her personal development.

Her responsibilities often position her as a liaison between field operations and bureaucratic functions. She supplies necessary equipment and tactical information to agents like Daisuke and J while simultaneously striving to enforce procedural compliance. Her duties occasionally extend into active field operations, demonstrating capability beyond administration. She participated in resolving a bomb threat and later rescued Daisuke during a critical mission.

Physically, Kyoko has distinctive pink hair, green eyes, and is frequently depicted wearing a choker. Official sources note her age as 21 years old. Information regarding her family background, upbringing, or life outside her professional role remains unavailable.

Her character development centers on evolving professional relationships and emotional adjustments. While her foundational traits of diligence and rule-focus persist, interactions, particularly with Daisuke, contribute to subtle shifts in her interpersonal dynamics.