: You can proceed with standard unlocking methods.
Unofficial methods may permanently brick your device if done incorrectly. docomo unlock bootloader install
Unlike global versions, Japanese carrier models from Docomo, Softbank, and Au are notoriously "hard locked". The standard "OEM Unlocking" toggle in Developer Options is either missing or greyed out, and the official Sony Bootloader Unlock website won't provide a code for his IMEI. The Quest for a Workaround : You can proceed with standard unlocking methods
Download the latest ADB and Fastboot tools to your PC. The standard "OEM Unlocking" toggle in Developer Options
Unlocking wipes all user data (factory reset). ADB & Fastboot: Install the SDK Platform-Tools on your PC.
that allows bootloader unlocking on these specific older series regardless of the "No" status. Check the Xperable guide on XDA for step-by-step instructions. Paid Services (Hit or Miss): In the past, tools like S1 qUnlockTool