Yūko Shionji, known solely as Alice, operates as a self-styled NEET detective. She lives in isolation above the Hanamaru ramen shop, having fled a wealthy, restrictive family at an unknown time. Her true age is undetermined, though her appearance suggests a 12- or 13-year-old girl: pale white skin, long black hair in a hime cut with square bangs, and blue eyes. She is almost always confined to her cluttered room, filled with computer monitors and stuffed bears, typically clad in bear-patterned pajamas, shorts, and white thigh-high socks. For rare outdoor excursions, she adopts elegant gothic lolita attire or a formal black kimono during significant Hirasaka Group ceremonies.

Alice sustains herself on Dr. Pepper (DokuPe in the anime) and specialized low-carbohydrate meals from Hanamaru, like noodle-less ramen broth. She suffers severe insomnia and actively avoids basic self-care such as bathing or proper eating, often needing intervention from Min or Narumi Fujishima; Narumi sometimes withholds ice cream to coerce her into consuming vegetables. Her personality blends intellectual brilliance with social ineptitude: she demonstrates exceptional deductive reasoning and hacking skills to solve cases remotely, yet communicates with blunt sarcasm, often frustrated by others' inability to follow her logic. Despite this abrasiveness, she awkwardly displays care for associates and maintains strict impartiality in investigations, calling herself "the speaker to the dead."

Leading the NEET Detective Team, Alice directs field operations via her network and computational resources from her room. Her cases delve into dark societal undercurrents—drug trafficking (like Angel Fix), gang violence, and suicide. Key investigations include uncovering the reasons behind Ayaka Shinozaki's suicide attempt and amnesia, locating Meo Kusakabe's missing father, and dismantling Hirasaka-linked criminal operations. Her methods sometimes involve psychological manipulation, like delivering despair-inducing final words to a dying antagonist. She demonstrates unconventional problem-solving, such as inserting herself into a baseball game as a batter, exploiting her small stature to create fielding errors and secure victory through strategic observation—a successful Batman Gambit.

Her relationship with Narumi evolves significantly. Initially viewing him merely as an assistant for errands and technical support—repairing stuffed bears or managing basic computer tasks for the technologically inept Hirasaka Group members, who call him "God Hand"—she gradually develops reliance on him for operational support and personal interaction. Subtle moments hint at a growing connection, like indirectly sharing a drink. Her background remains largely mysterious, even to close teammates; she acknowledges her self-imposed exile from her family and expresses no desire to reconcile with conventional society. Despite facing high-stakes criminal confrontations that challenge her detachment, she maintains her reclusive lifestyle and NEET identity as fundamental.