@BigJoe4243
That's not the warcrime part. Cutting off supply is standard warfare tactic.
Using poison and biological attacks against soldiers IS a warcrime. Sure, not by their standards (used to be a popular tactic - get some rotting carcasses onto catapults and pelt a castle or town with them to either force them out or try and spreading some disease to kill off/weaken defenders), but Kaoru comes from a pacifistic Japan so she should recognize or at least feel SOME remorse over using diseases to fight enemy.
And she's not using equivalent of tear gas to neutralize enemy relatively harmlessly. It's more like using airborne viruses to cause diarrhea and vomiting, both potentially lethal for soldiers marching in hot temperatures with gear. She's not even doing it to protect her people, and if she has such advanced potion-creating skills then she could've dealt with them in MUCH better ways. Like, I dunno, Tanglefoot Bags that would impede their movement and force them to drop armor and gear they've lost, or something to knock them out and render unconscious forcing to retreat.
What she's doing right now is basically torture. I can't believe Kaoru got THAT attached to the country to make hundreds or thousands of people suffer like that...
@chickenduy
Scorched earth tactic means burning your crops and destroying water supplies, sure. It doesn't mean "use magical potions to induce vomit and diarrhea. There's little difference between this and biological warfare, using germs to induce those symptoms.