Data Center/World Allowance

Yes, I started playing FFXIV back in 2011 with 1.0, a lot has changed since ARR, so consider my coming back as I'm a newb to ARR.

While I get around quite well, it isn't very clear to me if I am allowed to create a character and play on worlds from data-centers not for my region.

For example: I like Japan very much, as I do like FFXIV very much. Of course I would like to make friends with Japanese people through this MMO like I could in 1.0, but since the data-center implementation I am not sure if I am allowed to.

Can someone clear this up for me?

You can play on a japanese server if you desire. The region split is mostly so people can have a server located closer to them for less latency and also to gather people that are roughly in the same time zone and a higher chance that you will speak the same language as most people on the server.

A tip if you do decide to play on a japanese server: make sure you enable the J in the duty finder queue menu so you will be paired up with Japanese players. Otherwise your duty finder queue will not place you in those parties when they are a majorty of what will be available on those servers.