I think I recently read that you can go ten days without food, before serious trouble hits, but it’s three days without water that leaves you loopy, and after a week dead.

You see it in a lot of different stories, the summoned Japanese people obey the law, for the most part, and so they just get used to the existence of slaves, or mistreatment of other races.

You’re overestimating modern people. He’s in a strange unknown world. Not many people would throw away stability and safety when the future is so unsure. Not to mention the other side are non humans.

If human treat EVERYONE better cause since he is bound to rebel as he have modern day sensitivities.

If the humans treat him better he would probably not threw his lot with the beastmen like what the narration suggested in the beginning.

It’s possible, the 7/21 Is just a rough estimate. Of course, your body will start converting everything from fat and muscle to energy if you’re actually dieing from starvation, and your body will be completely ruined after a certain point…but I digress. You’d usually die earlier though from something like a weakened immune system or some other sort of complication.