Gantz tells the story of Kei Kurono and his friend Masaru Kato who die in a train accident and become part of a semi-posthumous "game" in which they and several other recently deceased people are forced to hunt down and kill aliens armed with a handful of futuristic items of equipment and weaponry.
Mix 'em up with Matrix, where you will see politics, blood, nudity and not so kind main male character. And when Gantz make appear a character it is so detailed.
the story really is unique, i mean people who die get ressurected by a big black ball to kill aliens? AWESOME
Hearing the thoughts of the main character is also lots of fun since he's a real meanie and a perv (watch ep1 and u will know what i mean) lol. Beware! the ending differs from the manga, in the manga the story is still ongoing. You should defenitly try this anime out.