User blog comment:Roranoa Drake II/Chapter 790: One Punch/@comment-180.193.123.171-20150619053608/@comment-10543621-20150621232348

Let's see... I'm gonna give a shot at their association with the countries they're depicting.

Sanji with France: Easiest one out of all. Despite his name being positively Japanese, a lot of other things about him has French influences. His attacks are mostly French culinary terms of some sort.

Nami with USA: Uh... I really can't scratch any connection here. Apart from who doesn't like a hot full chested cowgirl from Texas?

Luffy with Japan: Luffy himself isn't very Japanese, but it would of course be fitting for the Captain to depict the country of origin of the Manga itself.

Usopp with Brazil: This is a bit of a stretch, but I guess his time spent in the jungle training and his usage of different plant forms might be able to be loosely linked to the Amazon rainforest as one of the places with the greatest biodiversity in the world. That and the samba outfit suits him.

Franky with China: This one is quite opposing to be honest considering how Franky's persona is extremely USA. I guess if Oda wanted to use the extreme stereotype of a kung fu girl with ridiculous ponytails, who better to depict that than Franky? He's a hand to hand combatant (when he's not blasting missles and lasers) and he has the ability to change his hairstyle, so that makes perfect sense.

Brook with Britain: He likes drinking tea and he's a rockstar with an afro. Plenty British enough I guess.

Chopper with probably Canada: That's definitely an Inuit theme, which obviously suits Chopper as a reindeer. Then again, it could fit any far North territories with Inuit influences including Siberia or other parts of Europe.

Robin with India: Apart from the fact that she's sizzling, her ability to sprout many arms is reminscent to plenty of Hindu deities as others have mentioned.

Zoro with German: The beer stereotype. Need we say more?