[PapaBear3625]

The weapons used in war must discriminate between combatants and non-combatants. Civilians are never permissible targets of war, and every effort must be taken to avoid killing civilians. The deaths of civilians are justified only if they are unavoidable victims of a deliberate attack on a military target.

So an 18-year-old draftee is a legitimate target, but the civilian leadership which ordered him to fight is not?

[narses]

Arguably civilian leadership can be seen as combatants, but the general usages of modern warfare prohibit deliberate targeting of civilian leadership.

In this case the 18 year old Japanese soldier or sailor was a correct target, their aged grandparents and infant siblings were not.