That depends on how badly you’ve blown up your equipment. Inspection is needed to determine that.
If you don’t know, Japan uses a mains supply rated at 100 Volts. The USA uses 120V. These supply voltages are 100% incompatible with Australian 240V mains. If you plug in a piece of hi-fi equipment that is set to run on 100V here in Australia for example, IT WILL FAIL, without exception.
Electronic equipment does not “automatically adjust” as one customer who blew up his gear suggested to me. He may have been thinking about cheap equipment with switching power supplies (SMPS) that accommodate a wide range of input voltages and can be used around the world, like phone chargers for example. Virtually none of the hi-fi gear we are interested in uses SMPS.
At a minimum, have new equipment checked to ensure it is configured to run on 240V. Some equipment can be configured to run on a variety of line voltages, and some cannot. Sometimes the adjustment is external, other times it requires soldering inside a chassis. This is not something you can have a hunch about. Guessing on this is not an option!
“But Mike, it will cost me money to have my equipment checked and reconfigured..!”
That’s right, and it will cost you a much greater amount of money if you plug it in and it fails. It’s really about being sensible.
If your new equipment cannot be reconfigured, then a step-down transformer will be needed. There’s an FAQ for that.