Well, without more context, it's hard to say precisely. It might be a spin - off story that delves into the afterlife or the stories of characters who have died in the main Jojo series. It could also be about a new threat or mystery that is related to the dead in the Jojo world. Maybe it has something to do with a particular villain's plan that involves the dead.
The 'jojo dead man's story' could be a story that explores the concept of death and how it relates to the Jojo universe. It might follow characters who are dealing with the loss of their loved ones who have become dead. It could also involve some sort of supernatural or Stand - related phenomenon that is connected to the dead. For example, there could be Stands that are powered by the souls of the dead or that can manipulate the dead in some way. There may be a journey that the characters have to take through a world filled with the dead, facing various challenges and uncovering secrets along the way.
I'm not entirely sure as it might be a relatively specific or niche part of the Jojo universe. It could potentially be about some sort of dark and mysterious adventure involving Jojo characters, perhaps with a focus on the undead or some macabre elements.