The real person was called Viktoria Luise, and she was Prussian, and she dressed like this in her Prussian Death’s Head uniform:
The fictional character was called Nonon, and her uniform was obviously based on the Prussian Death’s Head uniform.
And her theme is this:
And the blogger who doesn’t recognize her is at:
And you really should watch Kill La Kill to get to know her character.
And after you have watched the whole series, then, and only then, can you do a websearch for “nonon cosplay.” Just make sure you’re in a private place when you do that websearch. Or in the company of close personal friends, who won’t judge you. Because most of the cosplayers who dress as Nonon prefer to dress up in her other uniform.