Australian passport holder wanting to visit China, currently in Japan

Hi! I'm an Australian currently in the countryside in Japan and have a flight booked back to China on 16th October. I previously have had two Z issued to me as I was working there. I plan to go back for 4 weeks to visit my boyfriend (we will visit Hong Kong in this time, so I know I will need a double-entry) and I have proof of my flight out of China back to Australia as I continue my travels until April next year when I will come back to China (hopefully with a job offer and a new Z-visa!).

My question is what is the best way to apply for the visa? I fly out of Osaka on the 16th, but I am currently staying a good 10 hours from there, and about 5 hours from Tokyo. I plan to stay here until about the 12th October, meaning that (due to the weekend) I would only have the Monday 15th and Tuesday 16th (I fly in the evening) to get it. Is this possible? And if so, how much extra would it cost? The only other option I can come up with is to travel down to Tokyo and drop off my application, and then travel down again a few days or a week later to get it (but this is very expensive as Japanese transport is not cheap!).

I gathered from reading the questions above that because I'm only a tourist in Japan, that I need a travel agency to apply for it. Is this correct? What type of travel agency would I need, can you recommend one?

I'm sorry, this is a long question and quite complicated! It's just an unusual situation and I want to make sure that I can get into China as easily as possible!

Thank you so much for your advice in advance :o)