Saizo Yui is a single, 29-year-old woman who works in the crime laboratory at the Takanashi Police Station as a forensics examiner. She does her job well, due to her excellent memory and analytical mind. She prioritizes efficiency at her work. She also eschews the old-fashioned and traditional ways at the police station, like, working overtime or being liked by colleagues. She does have two close female colleagues at the police station. They are Kira Masumi and Motoyama Iori. Kira Masumi works as a physician in the medical office, and Motoyama Iori works in the traffic department. Every Friday night, these 3 women gather at an izakaya pub and chat about everything, including work and relationships. One Friday night, during the course of their normal conversation, they talk about a case that detectives at the police station are having trouble solving. Since then, they have talked about difficult cases and tried to solve them using their respective talents. (Source: AsianWiki)