Ajin is a show about these being called Ajin which are black ghosts which are inspired within humans because of this ability they won't be able to die.
I have just watched this show and I have to say it's very good and interesting. I even like the 3D/CGI animation it has to it. I have watched many different 3D/CGI animated shows such as Green Lantern the animated series, Beware the batman, Spider-Man 2003, Star Wars the clone wars and a little bit of Star Wars Rebels.
But I have never came across an anime which was an anime which is CGI or 3D animated and it's definitely a nice change of pace then the same 2D animated or different use of colours which I see a lot in animes.
If you want something 3D animated with a dark story then I would recommend it.
Now I just hope there is a season 3 in the works so the series can end on a proper note. If you are going to watch this show expect an ending which would be left on a cliffhanger which may take time to resolve.