NZ citizen here.
You don't need a visa for Australia as you're in transit, and even to visit don't require one.
As a tourist in Japan, you need a flight/boat trip/etc out of the country, but otherwise can have up to 90 days.
Source: Have visited, transited and lived in Aus, and visited Japan four times, on a NZ passport.
As a New Zealand citizen you won’t need a visa for Australia as you don’t plan to leave the airport and will only be there for a few hours. If you do choose to take a longer layover (8+ hours) or leave the airport you can get a SCV visa on arrival by filling out a landing card.
You don’t need a visa for Japan either as you are going for 90 days or less, ...