The history geeks of Girls und Panzer's Hippo Team aren't an original concept. The label "reki-jo" has been coined for the subculture of "history-loving girls (rekishi-zuki no joshi)." And the Japanese Sengoku and Bakumatsu subjects of their fascination are very stereotypical of their brand of otaku.
Plastic model maker Platz is helping GnP watchers join them in the fandom with life size (600 x 1800mm) reproductions of their tanks banner.
From the OVA