I know what you mean, but I don't have an answer myself.
Really the collateral damage in Ukraine is still ongoing, not in Tokyo for quite some time.
So it's tragically possible that Ukraine could end up worse than Tokyo by the time hostilities finally cease.
Maybe with Tokyo a closer equivalent might be if Ukraine attacked Moscow using a comparable approach, with a degree of disregard for collateral damage figured in. Although Russian strategy already seems to target any part of Kiev that can be hit, civilian or not.
Plus no two things like this are really on the same scale and it's never a direct comparison, but there's some common undercurrent that is either predatory or vengeful which sometimes can grow until it can't get much worse.
So what about prehistoric tribes, even pre-humans, who surely had occasionally completely massacred victim tribes from time to time, not much differently than pack animals have always been known to do.
Total extermination like that could be rapidly completed with no weapons of mass destruction or even gunpowder.
Isn't there some possibility that this tendency has been retained evolutionarily or culturally to some extent today, even though most people would say that's just the opposite of "humanity".
Passed down in an unbroken chain in some way?
Disclaimer: when I was a teenager I worked one summer with a German machinist who had survived the bombing of Dresden. Ironically the project we were on was components for the the most advanced projectile of its caliber, yet to come. Both of us would have liked to build something else, but most opportunities across-the-board affecting all ages had already evaporated due to inflation of the 1970's, and the runaway years hadn't even gotten there yet.