Rei Hidaka, a 25-year-old developer at a beauty research institute, possesses striking blue hair trimmed to ear length and vivid red eyes, standing at 177 cm. Born January 5 under the Capricorn sign, his demeanor blends assertive independence with introspective tendencies, maintaining reliability toward trusted companions while often seeking solitude. A former track and field senior alongside Ryo Fujihashi in high school, their past romance resurfaces with unresolved tension, marked by lingering emotional undercurrents and Rei’s protective loyalty juxtaposed with guarded vulnerability.

His reserved exterior masks a passionate core, evident in moments of interpersonal friction or romantic rivalry. Professionally dedicated yet privately inclined, Rei balances meticulous formal attire and glasses with casual interests in cooking, reading, and music—frequently seen with earphones. While impulsive reactions surface when threatened, his role as a romantic foil centers on contrasts between restraint and intensity, serving as both a catalyst for conflict and a mirror to unresolved emotions. No additional details contextualize his family, post-high school education, or extended personal growth beyond this narrative function.