You don't pre-order "for a data center". You pre-order for the region that you live in.

If you are in NA but play on a JP Data Center, you would get the NA version.

If you are in Japan and play on a JP Data Center, you would get the JP version.

http://store.jp.square-enix.com/
http://store.na.square-enix.com/
http://store.eu.square-enix.com/

Make sure it matches the region of your account, but this would normally be the region you live in because all of your details that you put would be for that region.