JAPAN

You must have a valid passport to enter Australia.

To enter Australia, a pre-arranged entry authority known as an 'ETA' (Electronic Travel Authority) is required. An ETA is equivalent to a visa, but there is no stamp or label in your passport and there is no need for you to visit an Australian diplomatic office to submit an application. 

Most U.S. passport holders traveling to Australia for tourism or business purposes for less than 90 days can obtain an (ETA). ... Visit the Embassy of Australia website for the most current visa information.

English is the common language of Australia. However, as Australia is a multicultural society, you may hear other languages spoken.

It is safe to drink tap water anywhere in Australia. Bottled mineral water is available throughout the country.

Vaccinations are not required unless you have come from, or visited, a yellow fever infected country or zone within six days before arrival. No other health certificate is required to enter Australia.