I'm looking at a flight that goes from Auckland to Brisbane, 1 hour 15 minute layover and then goes from Brisbane to Narita airport in Japan. Would the layover time be enough? The airline is Qantas and I assume it's one ticket as I'm looking at it in Google Flights.
Presuming your inbound flight is on time, this is a very achievable connection.
On the basis that it's all on one ticket your bags will be transferred for you. You will need to re-clear security in Brisbane, but will NOT need to pass through immigration or anything else.
The risk is that if your inbound flight is late and you do miss the connecting flight then you will likely need to wait until the next day to get on a flight. If you can't handle that long a delay, I would suggest booking a longer connection.