In 1940s Japan, the wealthy head of the Inugami Clan dies, setting off a chain of bizarre, gruesome murders. Detective Kindaichi must unravel the clan’s terrible secrets of forbidden liaisons, monstrous cruelty, and disguised identities to find the murderer.

Jun Hashimoto is a sci-fi novel writer, but he isn't popular at all. He lives off of his savings. One day, his editor Tateyama assigns him a job: he is to write a "love" themed short story for a web magazine oriented towards youths. At first Jun refuses, because he has never written a love story before, but Tateyama pushes him to write one. The deadline is imminent. Jun's childhood friend Keisuke Murata then appears in front of him. Jun complains to Keisuke that he can't write, but while talking to him, he comes up with an idea.