Final Fantasy XIV: A Realm Reborn is due to be released in 1 week from now for those that pre-ordered, and 2 weeks from now for non-preorders.
If you are at all into MMO's then this could be an amazing opportunity for you to study Japanese and play at the same time. This particular game has a very large Japanese player base, and since it has been designed from the ground up to be localized in several languages the customization options are quite nice indeed. The servers for this game are separaed by either NA/EU or JP. For those of you wanting to study I would highly suggest finding and playing on a Japanese server. This will be available during the character creation process.
From there I can see three basic playing styles depending on you level of Japanese. If you are a beginner then you can use the English interface and join English linkshells/guilds. You will still be exposed to Japanese in general chat channels since you will be on a Japanese server, so you'll have ample time to go through your chat log and try to read things you see. You'll also still be able to group with JP players. Thanks to a built in auto-translate feature you will still be able to communicate important things with your party if needed.
The second option would be to use the English interface, but instead of joining all English linkshells/guilds you can step it up and join some Japanese ones as well. This will give you the opportunity to be more interactive with the Japaense community and talk with your guildmates. You might be surprised how open most people are to having you in their shell.
The final option would be to switch to the pure Japanese interface. From here you could either go with English or Japanese linkshells/guilds as your entire game will be in Japanese; though I'd still suggest a Japanese shell if you are this far advanced in your studies. This of course would also be good for beginners or intermediates if you just want to dabble. It can be a bit overwhelming if your kanji isn't at least at N3 level, but still excellent practice.
The main story cutscenes will give you the option to choose voice-over and subtitle langauges regardless of which interface you select. I would suggesting English subs on this if you can't fully understand the Japanese only because the main story lines are amazing.
On a final note, I would strongly suggest a Japanese keyboard if you can afford to get one. Having your system set up to work with a 106/109 key JP keyboard makes transitiolning between the langauges/Kana in your IME far faster.
Feel free to PM me if you have any questions on the game.