Call of Duty Black Ops 3 Beta Free - Xbox One

No code required.
On your Xbox One:

1. Go to settings, System, Set Language to Japanese.
2. Go to Marketplace, search for it, and download it.
3. Change back to original language and play.

On your PC:

1. Go to either the link above or this: https://store.xbox.com/ja-JP/Xbox-One/Games/Call-of-Duty-Black-Ops-III-Multiplayer-Beta/3aff42d2-453c-437a-a489-c49a7b068e84
    
2. Make sure the link still contains ja-JP, if it does, skip to step 4.
3. (opt) If ja-JP is not there, go to bottom left and change language to Japan.
4. Download it.