The FOMA debug cable (unofficial name) is a modified version of a regular FOMA cable that allows special access to most Docomo phones and some SoftBank phones. This cable modification can be performed at home with a soldering iron. It is also available for purchase at The GameTank Store.
Connect USB power (pin 4) to FOMA power (pin 5), and connect USB ground (pin 1) to FOMA ground (pin 10) as well as pins 8 and 9. Pins 2 and 3 are standalone and are just used for USB data. For some cables such as the “02 Connection Cable” or Elecom FOMA adapter, you only need to solder 8, 9, and 10 pins.