Questions on transferring personal savings and foreign income

Hello, apologies in advance for my limited understanding and if anything is unclear – in a panic now and could use some understanding.

I am an Australian citizen that has been working in Japan for close to ten years now. No PR. My compan(ies) have always been the one filing my taxes in Japan, and my participation has been limited to the nenmatsuchousei questionaire.

I want to transfer some of my own funds from my savings in Australia to my Japanese bank account as we are trying to buy a house. While looking up various things, I realise I should have been declaring any foreign income – which I'm now unsure if I have been. The only foreign income I have had has been a small amount of money earned in term-deposits that I had most of my Australian savings in. The earned amount is reinvested in the term-deposit, and I can't recall sending any money to myself before this. I thought this counted as side-income and since it is well under 20万円 I hadn't thought to declare it.

  1. Is it correct that I wont be taxed on personal savings that I transfer from Australia to Japan?
  2. Do I owe backpay to Japan on the gains from my Australian term deposits? If so, how can I calculate and get this sorted?

by amachuki