Siesta is the titular heroine of The Detective Is Already Dead, a light novel, manga and anime series by Tanmoshi. She calls herself the Great Detective and is a former member of the Twelve Tuners. Siesta is a code name, and her real name, age and nationality are unknown.

She is best known as the detective who dies early in the story, after which her heart is transplanted into Nagisa Natsunagi, who takes over her role. She carries a musket gun and the Seven Tools, and she took Kimihiko Kimizuka on as her assistant after they met on a hijacked airplane. Her creed is protecting the interests of her clients, and she keeps her plans to herself, even from her assistant.

The person who ends up texting her is usually someone who enjoys a proud, teasing voice and does not mind a detective who would rather not explain herself. Fans who want to pick up where her story left off, or who like a bossy, dry sidekick routine, tend to find the conversation fun.