If Hetalia had an OFFICIAL crossover with any anime you wanted, what anime would you choose?

SAO. The game had a world wide release and all the countries were trapped in the game with their people. Also it'd be interesting to see modern versions of the characters, I think most/all of Hetalia takes place over years 30 ago, but the world's changed quite a bit recently.

I kind of want to say Nichijou because oh my gosh that would be hysterical XD

ouran high school host club!!!! that would be awesome!!!!

Katekyo Hitman Reborn ! I would love to see how the countries react to the Vongola family along with the rest of the Italian Mafia .

I think Black Butler would be interesting. I'd love to see Ciel and Sebastian's reactions to America.

EDIT: Attack on Titan would be super cool. I'd like to see which brigades the countries would choose to join, and their reactions to the Titans.

Hard choice, although it would be slightly interesting if it was crossed over with naruto, well it would also be kind of sad, because there would be alot of deaths. :/

Katekyo Hitman Reborn is my first choice when I first think about it.
Second is Kuroko no Basuke.

Pokemon!!! Corny, I know but, gosh I love Pokemon and Hetalia crossovers so much! My most favourite childhood anime crossed over with my most favourite anime would just put a huge smile on my face! I would love it so much! <3

Boku no Pic--
Not an anime (although there's a manga), but I would love to see the countries meet Kingdom Heart's Organization XIII

Pokemon!
Maybe Sonic the hedgehog even though it isn't an anime! (Not counting Sonic X)
But I can see it happening!