Convert Australian license to Japanese

Hi guys, i've a question. As i'll be going to Japan for University in March 2012, i'm interested in converting my driving license to a Japanese one. Here's the scenario, i've obtained a Singaporean driving license in feb 2011, but have stay in Australia till Oct 2011. in Sept 2011 i had gotten an Australian driving license. And since i've been back from Oct 2011 and will be in Singapore until Mach 2012, As one is required to be in the country for at least 3 months after issued of the license, whereby in this case my singapore license has qualified right?, however the question is can i use my Australian driving license instead to convert to a Japanese license without taking the written and practical test?

As one is required to be in the country for at least 3 months after issued of the license, whereby in this case my singapore license has qualified right?

Yes, September to March is more than 3 months.

however the question is can i use my Australian driving license instead to convert to a Japanese license without taking the written and practical test?

No, you did not stay in Australia for more than 3 months after getting the Australian license.