Hi @Maliciousmonk,
A warm welcome here in the Roku Community!
We're glad to assist you with your inquiry. Kindly check the back of your Roku TV or in the box. There should be an indicator as to how much voltage is required. Also, the mains power in America is 125V while in Japan it is 100V. The voltage difference will likely not be a problem, the wildcard is the Alternate Current frequency: in America its cycle is 60Hz, and in Japan it is both 50 and 60Hz depending on your location. This means that you will not need a converter or transformer but just a travel adaptor, because Japan operates on a 100V supply voltage, which is within the 100-240V range that the dual voltage appliance operates on. When comparing Japanese outlets vs US outlets, the two are almost identical.
If you need anything else, please don't hesitate to reach out to us again.
Best regards,
John
John
Roku Community Moderator