Yūta Sasaki is a 15-year-old boy serving as secretary for the Inaba Detective Agency. He sports a distinctly feminine appearance: short blonde hair partially obscuring his eyebrows and neck, light blue eyes, and an innocent facial structure. His typical outfit consists of a light pink shirt layered over a dark top secured by neck straps, a white belt, a short blue skirt, beige leg warmers, and brown heels, reflecting his cross-dressing identity. His personality reveals sharp duality. Yūta maintains a gentle surface marked by a constant smile and frequent adoption of cute anime girl mannerisms, especially around Hiroshi Inaba, toward whom he directs affectionate, unreciprocated gestures. This contrasts violently with a pronounced sadistic streak unleashed against those he dislikes, particularly Kuniharu Ogino. His resentment toward Ogino, fueled by jealousy over Ogino's past partnership and mutual trust with Hiroshi, erupts in verbal sarcasm and physical aggression, including attempts to harm or kill him. Professionally, Yūta volunteered as Hiroshi's assistant, claiming unparalleled understanding of him. His devotion borders on possessiveness, triggering extreme protectiveness and jealousy whenever Hiroshi interacts closely with others. He later forges an alliance with Noah, a member of the rival Valentino mafia, united by their shared goal to eliminate Ogino. Despite their opposing factions, they text frequently, and Yūta exhibits protectiveness toward Noah, once calling himself Noah's "rival," hinting at potential romantic feelings for both Hiroshi and Noah. Yūta wields proficiency in "Hamusenryū," a deadly finger-based martial art capable of both lethal strikes and restorative healing. This skill enables him to transform Hiroshi into a werewolf by targeting specific pressure points on Hiroshi's back, granting access to supernatural abilities. Details of his life before joining the agency remain unrecorded. Within the series, early interactions establish his hostility toward Ogino, such as trapping him underground during a case while taunting him. His alliance with Noah develops later, adding complexity to his relationships. Yūta stands 152 cm tall, born December 23rd.