Very easy to teach English. Won't make much money doing it though. Plus, it's demoralising work. These 'English schools' mostly prey off fresh off the boat Japan enthusiasts and know that all employees are easily replaceable with the next wide eyed gaijin looking to live in Studio Ghibli land. You are just a cog in the machine. Do you have any sort of career in Australia? If so, you really willing to sacrifice it just to have a Japan experience? It's either a young man's game or a retired man's game. It's not a great idea to do as some mid-life crisis experience. You'll just end up worse off at the end of it. Can't you just visit the country?Does anyone know how hard/easy it is for Australians to live in Japan for a couple of years or so? We both can teach English. We might buy a cheap house and an appartment and rbnb it or maybe something else while the children go to school and learn Japanese. I'm just brainstorming at the moment.
English teaching (and take this from someone who did it for over 10 years) is a dead end and demoralising job.
If you have no career at all the best option is try to get actual teaching experience and become an International School Teacher. Get a teaching license in Aus and work there for a year or so and then try to get jobs in international schools in Japan. They will pay a good salary and you'd also likely get some discount on your children studying at the same school.
Don't let wanderlust for Japan overcome common sense.