Unlocking the bootloader and installing custom software on devices is a complex process often distinct from standard international Android models. While most Android enthusiasts are familiar with simple fastboot commands, Docomo-branded devices typically feature unique carrier-level restrictions that require specific procedures. Understanding Docomo's Bootloader Policy

Ensure the device is SIM unlocked first, as some paid bootloader tools require this status to function.

Unlocking a bootloader erases all data on the device. Step 2: Preparing the Device Bootloader Unlock: NO - General - Sailfish OS Forum