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I hope this is not a delusion but I recalled a B&W manga where the mc is a struggling mangaka that made a manga out of the encounter he had with a serial killer. And his work finally took off when he made the manga based of that. The main character in his manga is a murderer. One of the cases was the corpses of a family of four being made to sit in the dinner table as if a display of the perfect family scene. And then later on a serial killer who reads his manga and claims to be his fan reenacts it exactly as it is illustrated in real life. I don't remember if the killer in his prior encounter and said fan are the same person or not. It also had a movie adaptation I'm pretty sure but I can't for the life of me remember any title.