On the day Conan and his boy detectives protected the injured cat, the chief customer service officer, “Uranari,” was found dead in the restaurant “Bocchan,” which reproduced Natsume Soseki’s novel “Bocchan.” As the police investigation progresses, even the manager “red shirt,” who was thought to be a leading candidate for the criminal will be found dead the next day. The police think it was a suicide after they thought they couldn’t escape. However, Conan, who noticed that the body of Uranari had been moved, discovers that it was a disguise to make the “red shirt” that lived on the premises look suspicious.
At Ayumi’s suggestion, “We want to find the criminal who did something terrible to the cat!”, The Boy Detectives investigate the criminal, stopping Conan from trying to tell Kogoro and Inspector Megure.