Sherlock Shellingford is a founding member of the Milky Holmes detective team, hailing from a distinguished detective lineage. She inherited the "Toys" ability, granting extraordinary deductive reasoning and perception, which formed a core part of her identity and initial confidence.

Following a confrontation with the thief group Arsène, Sherlock and her team collectively lost their Toys abilities. Stripped of her defining power, she grappled with inadequacy and a loss of purpose. This forced her to confront her reliance on her Toys and adapt, learning to rely more on fundamental detective work, perseverance, and teamwork with her friends Cordelia Glauca, Nero Yuzurizaki, and Elly Cunningham.

Throughout subsequent challenges, including regaining her Toys only to face situations where they were ineffective or negated, Sherlock demonstrated resilience. She learned to value her innate intelligence and observational skills beyond her supernatural gift, understanding that true detective work often required more than power. Her deep loyalty to her teammates and unwavering sense of justice remained constant motivators.

Her background includes attending Holmes Detective Academy, where she formed the Milky Holmes team. Interactions with rivals like Henriette Mystère and encounters with antagonists contributed to her growth, teaching her humility and the importance of diverse perspectives.

In the alternative universe of "Tantei Opera Milky Holmes Alternative ONE -Kobayashi Opera to 5-mai no Kaiga-", Sherlock Shellingford exists as a celebrated opera singer, participating in the production of "Turandot". This version's role is distinct from her detective persona in the main continuity. Information regarding her background, life experiences, or development within this alternate setting remains unavailable beyond her participation in the special's events.