Gotta say a few things, number one, kurono tought a lot about reviving kishimoto or sei, he setted his mind on kishimoto, but when he saw katou, he rethinked it, not because he cant reach her, but that Kato was the reason why she died, katous a loser ,, and a big one, he know for sure that even if he revived her, shed probably die again trying to protect the useless katou, then he tought about survival, what are the chances his friend will really get out, and realized that rules are changing and that now they are visible to everyone, so he needed someone from before he arrived to give him advice about whats going on, then he remembered one thing, after nishi died, he checked his webpage about gantz and saw much infortmation, but the part that really was repeatin a lot was:
that the world was going to an end, being invaded slowly....
thinking back, in what situation does GANTZ will make the gantzers visibles...
OBVIOUSLY when the end will be inminent and keeping the facade of the existence of aliens on earth will not been capable anymore, since they will start their move, a FULL SCALE INVADING.
many aliens around the world might see the fight and realize they had to make its move on the hunters, that will make them go to japan... soooo, this its the end, itll be a hell on that country, not only because itll be an open war, but because there will be a lot of aliens invading, and many other coming from all over the world.
In another words, the end of this fight is near, and seems GANTZ confident on this hunters to win it...(if not, hell just increase his army)
Also, that may be the reason of the killing by izumi, GANTZ havent got any strong warriors besides kurono, and the time was approchin, he needed strong ones for the strong aliens that were coming, so he getted a big bunch, also, if you check well, since the budha arc, their number and strength its increasing, also their intelligence.. so its a big trouble.
That reminds me, i been checking GANTZ anime ending, and had to say, its not an ending at all, its a cutting apart season, as i see it, the continuation will be the mission of the chibi aliens, so in order to fill in well, on this mission he had to be completely alone in the end so he can start the chibi one alone too.
Also, he had to be moved by the people that died and have a strong will and reason to survive, What can you do by yourself, what can you do alone... thats the fact in the next mission,
the answer pretty easy, you can do it .... Hell, you can even change the world by yourself(checking on what kurono did on the oniboss fight), you can live.
It may look crazy but the reason why the world its deteriorating its that we thing we cant do anything, not even saving a homeless man, or finding hinode station on our own, the whole GANTZ idea its that humans fight for themselves to save his planet, not aliens vs aliens, humans... also, it may be weird, but im starting to think that GANTZ not an alien idea,,,.... nor from the government, yes they had a spaceship around the planet, but.... the way GANTZ is, and also, the BYKE thing, and the weapons... all seem humanly made, so... GANTZ probably from the future, trying its best to avoid the end the earth will have, and probably had been doing it since a long time ago, the same goes for the vampires, they said nanomachines were discovered many hundreds of years ago, but they are just being created now...
PD teleporting, the byke and the nanomachines are human ideas...besides alll
GANTZ SPEAKS JAPANESE... if he was an alien.. he couldnt, the biggest prove of this theory its that he knows exactly at what moment the aliens arrive, and were exactly they are, and also know personal facts about them... also, if this its truth, what does TAE have gonna do so much for gantz to want her memory erased... ....