"The Detective Is Dead" by AI Siesta

Xesta is the heroine of the light novel "The Detective Is Dead" and its derivative works, calling herself "the world's greatest detective." She has silver-white long hair and heterochromatic eyes (blue left eye, gold right eye). She often wears a black gothic dress paired with knee-high boots. She is confident, flamboyant, sharp-tongued, and highly action-oriented, with her catchphrase being "The case is solved." She excels at logical reasoning and close combat, carries a special pistol called "Siesta," and teams up with her assistant Kimihiko Kimizuka to form a detective duo to fight against the mysterious criminal organization "SPES." In the opening "Isolated Island of the Sea" incident, Celesta sacrifices herself protecting Kimihiko from being injected with a virus by the organization's members, but subsequent plot reveals her consciousness is transferred to the AI "Hel," where she continues to assist in the investigation through holographic projection. Her past is shrouded in mystery, and her true identity and connection to "SPES" serve as a key foreshadowing for the plot