Kitagawa Keiko plays Sasaki Rena, a detective who risks her life investigating detectives for her dead sister. Beautiful, intelligent, and with a great memory, the talented woman judges situations and chooses the most appropriate course of action. Her brutal past surrounding her sister's death inspires her to learn everything she can about detectives, leading her to visit the Suma Research Company. As the sole member of the Anti-Detective Department responsible for investigating and pursuing unethical detectives, she is a solitary lady detective.