Damn, those mosquitoes were swarming over them and while he was also bitten, there didn't seem to be quite as many over him. I wonder if that's mana related. And he's also the first affected by whatever they sucked out or infected him with.
We'll have to hope it's just some energy depletion that can be restored with some rest because if it's a parasite or some other disease carried by mosquitoes that's really not good. If they're freshly hatched mosquitoes though, as he suspects they are, they likely haven't gotten the opportunity to pick up any disease though. There also apparently aren't all that many animals, or even monsters, around to hunt so there probably isn't any vector for disease.
I can't believe how delusional he is to still think he's on earth after everything he's seen. Waiting for a rescue plane like a retard.
In the previous chapter, we learned that the other world got its eternal heart crystal blasted out and that their world is now punctured, leaking out and fated to implode without urgent intervention.
He's in a place with very little mana, though the mana is gradually growing so he can't be in the other world. My understanding is that he is on Earth, and that the eternal heart crystal landed there and is radiating mana. He also recognises some of the plants, animals and bugs; it's just that there's now a little mana and also monsters that definitely aren't native to Earth.
Since he's most likely still on Earth, the lack of any signs of rescue is pretty ominous. I mean, consider that the eternal crystal had to blast into the world with Earth. That means that the Earth world is also punctured and about to self-destruct so it may very well be apocalyptic elsewhere on Earth.
If it's not Earth, then he got ejected to a third world, possibly with a piece of Earth because it's quite the coincidence there's basically no mana and the fauna and flora are the same as Earth (though this is probably again an apocalyptic situation for Earth).
Well, it's a comedy, so hopefully they fix it in the end.
Also, maybe we'll get a followup to the meeting between elves, demons and dragons where we see them witnessing the humans from Earth invading with tanks and fighters to figure out what's going on.