http://www.degree-anime.com - They have all the latest chapters of Gantz all from 1-208

Starting from 205-208 Looks like "Muscle Man" defeated one of the Oni-bosses, Also Kei Kurono used his 100 points to get the strong weapon. Kei Kurono also met his brother but I dont think he even noticed and from what i've read the border between Gantz and the team is broken because everyone in the world can see them now. The people think of them as heroes lol. Now Kei and the team is fighting another Oni.

Edit: I just wanted to know, does anyone read this manga anymore?