Detective fiction is a huge genre in Japan. This probably isn’t that surprising, considering the consistent stream of Japanese mystery novels that get published, or the fact that Ace Attorney and Danganronpa are Japanese franchises, or that Detective Conan is a multimedia juggernaut. Mysteries are so popular, they even have TV shows where guests are confronted with a crime that they then have to solve.
Of course, actually finding time to sit down and watch a TV show can be a bit annoying... So what if instead of a TV show, we have a book about a TV show where contestants are given a murder mystery story and need to solve it? It's the excitement of a gameshow with the accessibility of a novel. Genius!
Hence, Mystery Arena was born. Maybe. (Probably not.)