"Pretend to be a detective, blackmail a beautiful wife who is cheating on you, and do it for free."

A detective is used to investigate his wife's cheating. This act seems like something out of a TV drama, but it's something I've been hearing a lot lately. So Dandy secretly obtains information about the target of the cheating investigation and investigates on his own. And once they have the evidence, the erotic blackmail begins! The guilt of having an affair and the unwillingness to be found out cause him to make unreasonable erotic demands.