Reiko Himekawa is just 27-years-old, but she has already received a promotion to become an assistant police inspector. She leads the 10th murder investigation team at the First Investigation Division of the Tokyo Metropolitan Police Department. Reiko Himekawa is an excellent detective and deals with many difficult cases. She works with Tamotsu Ishikura, Kohei Yuda and Shinji Otsuka on her team. The team then gets Kazuo Kikuta as a new member - a detective who does not talk much, but looks to do the right thing. A dead body is found at the park in Katsushika, Tokyo.