Sounds like you answered your own question. Why don't you transfer to a Japanese university to finish your Civil Engineering degree? From there the opportunity to work for a Japanese engineering firm or rail company would most certainly open up. I am imagine you would be employable in Australia as well since you can already speak English. The only problem I see with this is it would be expense to go to school there compared to the cost in your country. Good luck, let us know how it goes.