Device Transfer allows you to save game progress into a Square Enix bridge account and allowing you to move your progress to another device.
2. Create a new account. Change your country to Japan.
3. Enter username, password, email.
4. Confirmation code will be sent to your email address.
5. Enter the confirmation code and proceed. Account will be successfully created.
6. Launch DFF:OO. Go to the Settings (Gear icon) menu from Home screen.
7. Scroll down to データ共有登録・確認 and enter.
8. Login with the SE account created at step 1-5.
9. Enter the email address you registered with. Confirmation link will be sent to email.
10. Click on the confirmation link and the account will be "saved".
11. With the other device, just login into your sqex bridge account and you can now use your account to your other device.
Once your account is saved into an account, the save progress cannot be change to a different Square Enix bridge account.