I don't know.
Just a few things. The first two seasons are called Hetalia: Axis Powers (or Axis Powers: Hetalia), the third and fourth are Hetalia: World Series, it's not always set in WWII (ep.16 is about how China met Japan, for example), AMERICA IS THE HERO, all will become one with Russia, the dub is freaking awesome (THIS IS VUNDERBAR JAPAN), every episode is about 5 minutes, and of course.
[youtube]http://www.youtube.com/watch?v=Ym9GNtJadeg[/youtube]
Japan is the sexiest singer ever.