Not if the Japanese person was running at you with a weapon in-hand:
> In addition, the Japanese had organized the Volunteer Fighting Corps, which included all healthy men aged 15 to 60 and women 17 to 40 for a total of 28 million people, for combat support and, later, combat jobs. Weapons, training and uniforms were generally lacking: many were armed with nothing better than antiquated firearms, molotov cocktails, longbows, swords, knives, bamboo or wooden spears, and even clubs and truncheons: they were expected to make do with what they had.[63][64] One mobilized high school girl, Yukiko Kasai, found herself issued an awl and told, "Even killing one American soldier will do. ... You must aim for the abdomen."[65] They were expected to serve as a "second defense line" during the Allied invasion, and to conduct guerrilla warfare in urban areas and mountains.
> The entire concept of "war crime" is a post hoc rationalization for killing one's enemies after the conclusion of hostilities (see Nuremberg trials.)
The concept of universal laws of war to which all participants are bound and in principal accountable long predates the Nuremberg trials.
> Further, for much of human history, genocide (or the attempt thereof) was standard practice in warfare
For most of human history, slavery was a standard practice, both in and out of warfare, that doesn't make it right.
You seem to misunderstand me. I don't make an argument for its "rightness".
Rather, war crimes will always occur in war. And the primitive instinct to stay alive, at almost any price, is programmed into us. When faced with existential threats to our loved ones, these ivory tower questions about the relative worths of lives (100:1? 10:1?) are exposed for the nonsense they always were. Our biological programming kicks in: "survive at any cost - protect your own – eradicate the threat". It is only subsequent generations, from upon high in their ivory towers and far removed from the threat, who are able to condemn the savagery of the survivors.
In other words, it is always best to not enter a war. Perhaps even if attacked. 9/11 and the U.S.'s insane and disastrous responses in Afghanistan and Iraq being the latest demonstrations.
> In addition, the Japanese had organized the Volunteer Fighting Corps, which included all healthy men aged 15 to 60 and women 17 to 40 for a total of 28 million people, for combat support and, later, combat jobs. Weapons, training and uniforms were generally lacking: many were armed with nothing better than antiquated firearms, molotov cocktails, longbows, swords, knives, bamboo or wooden spears, and even clubs and truncheons: they were expected to make do with what they had.[63][64] One mobilized high school girl, Yukiko Kasai, found herself issued an awl and told, "Even killing one American soldier will do. ... You must aim for the abdomen."[65] They were expected to serve as a "second defense line" during the Allied invasion, and to conduct guerrilla warfare in urban areas and mountains.
* https://en.wikipedia.org/wiki/Operation_Downfall#Ground_forc...
At the very least it would be a form of self-defence.