Ryōko is an 18-year-old investigator with long burnt-orange hair tied in a ponytail and sharp indigo eyes. She dresses in a tailored forest-green suit and matching shoes, her appearance marked by a Queen of Spades tattoo on her thigh. Though she maintains a disciplined, professional facade, subtle moments of warmth occasionally surface during investigations, hinting at a gentler core beneath her driven exterior.

Her career path follows that of her investigator parent, anchoring her dedication to solving the enigma of Lost, a city erased from records. In June 2019, her relentless search collides with Shunpei Aoyama, a 22-year-old operative from the clandestine Agency. After she uncovers his ties to the group, he fatally stabs her in a confrontation.

Her name, リョウコ in katakana, holds no fixed meaning but invites interpretation through kanji possibilities: 良子 (virtuous child), 涼子 (refreshing child), 凌子 (enduring child), or others, each offering distinct symbolic layers to her identity.