Yeah, I gotta drop this one. I think the manga could’ve been better if author kept the tension building in the background a bit longer. Maybe let some characters die or go missing one by one, so the MC would gradually realize that his brother is behind it all. But it seems the manga already jumped straight into the 'all hell breaks loose' part and even that didn’t feel chaotic enough. So it ends up feeling like a half-assed attempt.
On another note, it seems like JUMP doesn't have any editors who can handle horror stories. They've had horror mangas with potential, but most of them failed in execution.