Connect your device using a high-quality or original USB Type-C cable plugged directly into a motherboard USB 2.0 port (avoid USB hubs). Step-by-Step Installation Guide Using Flashtool
If your device was previously rooted or modified, flashing the stock ROM completely removes binary modifications, returning the system status to official. Official Sony Xperia XZ SO-01J -Docomo Japan- Stock Rom
Unflashing mistakes or corrupted system files can cause your device to freeze on the Xperia logo. A clean stock ROM flash wipes the corrupt partitions and rebuilds them. Connect your device using a high-quality or original
Charge your phone to at least 50% to prevent unexpected shutdowns. A clean stock ROM flash wipes the corrupt
Download the official SO-01J stock ROM FTF file from a verified repository or via the tool.
If you are trying to resolve a specific issue on your device, tell me:
Sony uses (Flash Tool Format) for stock firmware.