You can't use the SSC Service Utility with the Epson PX-G920 (Japan ) because this device is unsupported. As far as I know, the SSC Service Utility has an option that allows you to use it with unsupported devices, but I wouldn't recommend it since it's an experimental feature that wasn't meant to offer expected results, therefore you should wait until the developers of the SSC Service Utility will implement the required functions.
Also, they recommend on their website to send an email if you want support for a device. Access their page to learn more about it.