Listen to yourself. You're trying to justify murdering civilians. That is not only a war crime, contravening the Geneva Conventions, but a crime against humanity.
Yes, civilians die in wars. That's called "collateral damage". Except that collateral damage means you were actively targeting military assets and civilian casualties occured accidentally in the process.
You know what we call purposefully targeting civilians, non-combatants, or neutral forces instead of hostile military targets in order to demoralize a foe and coerce a desired political outcome, such as a military surrender? Terrorism.
The firebombing of almost a hundred major Japanese cities is, to use your own words, a systematic atrocity. They weren't destroyed accidentally while targeting military assets, they were intentionally, systematically targetted - for a period of months - for the express purpose of spreading fear, panic, and dissent via the slaughter of civilians.
There weren't even any worthwhile military targets left to destroy - the Japanese military was in abject ruin. And even if it hadn't been, indiscriminate firebombing purely to destroy such targets with complete disregard for civilian casualties is utterly indefensible and morally bankrupt.
But the single most damning argument against your insanity? The Nanking Massacre was justified by its perpetrators with the exact same reasoning.
There are still individuals who maintain to this very day that the massacre was carried out against military assets - that any civilian casualties that resulted from it were mere "collateral damage", and consequently no crimes were committed.
There are also those who do not deny the targeting of civilians, but who justify it as a measure to compel the defeated Chinese (whose capital they had just captured) to surrender.
You are blind to your own double standard. When the other side does it, it is inexcusible and evil. When your side does it, it is necessary and justified, and not actually a crime anyway.
When they claim their side was just targeting military assets or just trying to end a war they had already won, you say they are lying. When you offer the exact same claims regarding your side, you refuse to believe those claims could be anything but pure, unvarnished truth.