[Korosensei wanted to 'die' - but not for death itself. He wanted to be killed by his students, to show how far they'd come, to prove themselves. He wanted death for what it would mean.]

Well... In my world, most people only really have kitchen knives? Sure there are soldiers and hunters and all, but the vast majority of people can count on their lives being peaceful.

[Nagisa is not 'the vast majority of people'.]

It would be nice if there were no wars, but... [Thinking that all seven billion people on the planet could get along for more than maybe a few seconds is naive.]