Do they have something in common?
Well, in chapter 229 Izumi and Nishi have this conversation:
Nishi: So how's this team?
They're no good under pressure.
If we don't get some better weapons...
Nishi: So it's too late for Japan even if we get our act together...
Maybe we should leave it to America, or Germany, or Israel or something?
Izumi: I'm Japanese. I want to show the world how superior Japan is.
Yesterday a friend came to my house. I was showing him this manga and I found this:
It seemed to be a special mission that Izumi remember and the main reason for him to go back to Gantz.
( BTW, It's from ch 119, when Izumi dates Kurono at school and shows him his little black ball...)
So the question is, do they have something in common?
I was thinking that maybe all Gantz teams from other country use to have a mission together where they compare results and see which team is stronger. That could explain why Gantz wanted strong people in the room. But think I'm just imagining things... The worst is that i've been thinking all this at work.
Ps: why has Izumi left Gantz? someone knows?
for the same reason that korono left. Izumi friends tells him that he do a grate job in figthing ... so he need to return back to normal.
Yet Nishi has ekpt his memories of Gantz, so there's something more to it.
This mission that Izumi remembers takes place in Japan (Shinjuku), and the people from that mission look Japanese too. So its hard to say that they are related.The point is that, some time ago, Nishi and Izumi were teammates, and then Izumi got his memory wiped out and left Gantz. But both of them know about the existence of Gantz in other countries. So there is something about this "old team" of theirs. Somehow they know too much. I suppose they were a strong team and they all managed to survive for a considerable time.
Maybe if you survive in Gantz for an extended period of time, little by little Gantz lets you know about the secrets. I mean, you gotta "deserve" it in some sense. Remember, the Kurono team did not know about the 100 pts menu at the beginning, but after the Tae mission they asked Gantz and he told them about it. Well this is still just speculation.
How Izumi and Nishi know about existence of Gantz is still a mystery though.
i don't really think gantz itsself holds back on information, it's just that nobody ever asks. as gantzers become more experienced they just seem to get smarter, and they start regarding gantz as more than a big weird black thing.