100/200VAC 50Hz or 60Hz is standard Japanese power.
If you could get a transformer that is ~40VAC and rated at the current of your appliance, you would wire that in a box to buck the incoming power. 1A should be sufficient. For example, this Triad part # FD8-48, about $20.
You connect the primaries in series (jump 2 to 4) across the 240V power, and connect 6 to 10 winding in series with the 240V mains. In one direction it will add, giving you about 288VAC, on the other it will subtract, giving you a reasonable 192VAC. Check with a voltmeter before wiring it to the fan.
It should be like this:
simulate this circuit – Schematic created using CircuitLab
Note: It might survive okay on USA-standard 60Hz 240VAC given the 50/60Hz compatibility, but personally I would not chance it without agreement in writing from the manufacturer.