there is no real Allied or Soviet analogue during the war to the Japanese treatment of POWs
What about the allied treatment of the German Aryan women?
Though at least Japan has yet to make an anime ABOUT the Nanking Massacre where they are the "good guys" who only killed "Military targets" like the good old Americans do.
Not systemic, not an organized and officially-condoned political institution devoted to supplying these women for the purposes of rape and sex slavery. The Soviets were the worst of the four occupying armies if you accept Beevor's numbers at face value, but even there, rape was punishable by anything ranging from arrest to execution. Similarly, American, British, and French soldiers also had punishments on paper for such crimes, though all three also had enforcement issues (the latter compounded by endemic race issues; black soldiers were more likely to be punished than white soldiers). It's the difference between non-enforcement of laws preventing rape and official endorsement of institutionalized rape as part of their military culture; both are completely and utterly reprehensible, but the latter is still worse than the former.
I'm not really discussing Kancolle in particular as being pro-Axis, myself; I was originally discussing how Neonivek is claiming that Japan has owned up to its crimes for the most part, that the Allies are the ones whitewashing their own crimes (which, in conjunction with the initial claim, also implies that they are the only ones whitewashing their crimes), and that he loves the romanticization of the Axis side in general. That disturbs me quite a bit.
The "punishments" for rape on the part of the Soviets were largely ceremonial, to put up a pretense of not being quite so bad as the Nazis. Various officers tried to actually prevent the rapes and punish the perpetrators but Stalin himself personally intervened in favour of the rapists at the time.
Anyhow, "romanticizing" the Axis is acceptable in my book so long it isn't romanticizing the crimes they perpetrated. I mean, I'm fine with viewing the Soviets from a positive perspective (or semi-positive anyway, since most Western and even contemporary Russian works acknowledge at least some negative aspects) so long as they don't start trying to outright justify or whitewash the Katyn Massacre, the Purges, the Holodomor or the rape of East Germany.
Besides that, I've always viewed the attitude of the Germans in overstating their own guilt and preventing the occasional neo-Nazi nut from saying his piece to be counterproductive and wrongheaded at best. The basis of freedom of speech is letting the dumbest, least popular view points have their say, and banning them so thoroughly makes them actually gain credibility for being "anti-establishment" instead of letting them be swept into the dustbin of history (honestly, if similar laws existed against being a supporter of Wallenstein or Tilly from the Thirty Years War, we'd be seeing a revival in witchhunts and religious extremism too). Mind, the Japanese went a bit far in the other direction by often completely ignoring their less savoury actions during the war, but the idiot nationalists aren't likely to gain too much traction, not in the least because American influence is basically the only reason Japan isn't an Autonomous Region of the People's Republic of China.