Arata Natsume Getting Married

Despite being in his thirties and unmarried, Arata Natsume is dedicated to his work at a child guidance center. His world is turned upside down when he is approached by Takuto, the child whom he once cared for, with a request to help him confront the murderer of his father - a notorious serial killer known as the "Shinagawa Pierrot" named Shinagawa Shinju.