This was a manga I read like 12 years ago so my memory is a bit fuzzy. A couple parts randomly popped in my head though and now I want to try and find it again. The general plot is that in this town a train comes by once a year or something and if you get on it will take you to paradise. The story follows one or two dudes who get on trying to get to the end but the entire journey is agressive trying to kill them. I think the first stop is a sort of rest station where people are given the option to turn back, but everyone who tries gets gassed or something. Another part, they're traveling through the desert and there hasn't been food for a while and people start dying. One group collects the bodies in the freezer and start eating them. I think they ended up turning into giant vulture monsters? It's not much to go by, I know, but if you know what I'm talking about, it'd be a great blast from the past for me.
wew couldnt find it through multiple searches as well as going past quite a few pages and searching on aggregators gl lol