The artist actually doesn't tag the picture as "Girls Und Panzer" or even give a character tag.
第二次世界大戦 - World War II 少女与战车 - Ambiguous tag in Japanese/Chinese mix having something to do with "young girls". ロシア軍 - Russian Military GIRLS - Ambiguous tag bringing up various pictures with girls in them. T-34 - T34
But given that the Pravda school logo is on the turret I'd say GUP tag is a go. Somehow overlooked that when I uploaded.
少女与战车 - Ambiguous tag in Japanese/Chinese mix having something to do with "young girls".
The pixiv tags "GIRLS" & "T-34" don't have asterisks. They've been tagged by someone else. 少女与战车 is the official Chinese title for "Girls und Panzer". See also its Wikipedia.
But isn't this an original themed on girls and tanks?
But isn't this an original themed on girls and tanks?
Honestly That's how I take it as well. Aside from the school logo on the tank everything appears focused on WWII. Even the title doesn't add up. Which is why I originally didn't suspect GUP.