Premise is a little weak, considering how most of the metals parts we use are already coated in something against corrosion. But it was an interesting manga
edit: 3 chapters forever
Remember kids: even without iron looting hooligans will fall before weak people working together. modern life might crumble without iron, but sociaty doesn't need telephones or tvs to uphold public order.
They basically said in the beginning that it's an alien bacteria that eats metals, which is close enough to "magic" as to allow for ignoring some of the fine details (like what the interactions with different anti-corrosion measures would be).
And I think it was supposed to be more than just iron, maybe all metals? I think iron is just coming up so much because it's the "big" obvious thing.
Yeah, this manga is really taking the Hobbesian (? I think I'm calling out my philosophers correctly XD) view on what would happen in a case like this. The authority is gone, everyone reverts to selfish animals!
For the most part, I would expect Japan to actually be pretty okay in a disaster like this, all things considered. It isn't really the country where I expect people to start rioting when public order is lost; the beginning of the first chapter seemed much more appropriate—that is, if anything, I would think the problem would be prolonged panicked inaction.
Also, the Japanese government is not so incapable that it can't send runners on foot (or after a little while on bicycles—someone's going to have a fiberglass one around, maybe you'd be stuck with makeshift wooden wheels which might suck, but...) with messages once they got their act together. They might send out bad advice, but the total communications breakdown doesn't make sense.
Some of the older generation should still remember living in a country that was coming up lopsidedly with growing pains; traditional farming and living techniques won't have gone by the wayside, a lot of things missing because of the lack of electricity could be compensated for...
Famine would eventually be a real problem because of Japan's reliance on food imports—they produce only about half(?) the calories they eat—I would expect rationing. And maybe some food theft. But not the sudden anarchy and civil war shown here.
...
But none of that really matters, I think. I'm pretty sure that the meteor and bacteria are just stage-trappings for a somewhat atmospheric, slow apocalypse story.
Which is to say, so so long as it doesn't stretch suspension of disbelief too much, at this point whether it's a good story or not is going to rest much more on how the character drama plays out within this context.