(Things u need: computer, iPod or iPhone, and ITunes on the computer)
1. Make entirely new email, only a yahoo or gmail one though. (Would suggest the yahoo email just because the gmail one sometimes doesn't work.)
2. Open ITunes and go to the iTunes music store and scroll down to the very bottom right hand corner and there should be a picture of your country's flag. switch it with Japan.
3. Once u have made your email and ITunes is Japanese, u will want to start beginning to make your Japanese ITunes account, enter all of that information such as your new email, password, security questions, (ect.)
4. After you have entered all of that information, a billing page will come up. U will see all the billing methods, if there is one that says "None" then you are successful! Click none and and enter the rest of your info. (This may help but the postal/Zip code has to be like this (Ex: 480-1234) and just enter your normal street name and pick any of the Japan cities) If I missed something on that page it is probably fairly simple to do the rest I have discluded.
5. After doing the billing info, verify your email. After doing so, log back in to your new email in the Japanese iTunes Store search brave frontier download it on your computer from iTunes.
6. When it's done downloading, go on your IPod or IPhone and go to the App Store. Once you log in to your new Apple ID, you will notice that most products on the App Store are now Japanese. Go to search enter brave frontier download it and there you go just sit back let it download and now you have brave frontier Japanese version for IOS!
(If you don't know how to log out of your Apple ID, go to the featured section on the App Store, scroll all the way down and click on your apple ID and hit sign out)
Hope this helped!
Credits to Viibrava.