Do one needs Chinese visa to travel to Japan by China Southern Airlines(Delhi-Guangzhou-Narita) ?

I also intend to visit China with my wife on my return journey from Japan to Delhi ( Narita-Beijing-Delhi) for a period of about 10/15 days ( Beijing/Shanghai and Xiang cities) in the month of Sept,2012 ( 8.9.12 to 18/20.9.2012). Can We get Chinese Visa at Beijing Airport on Arrival or we have to apply in advance at Delhi Centre before leaving for Japan in June,2012 ( 9.th June to be precise, please). The visa rules says one can not apply more than 3 months before, please. We intend to say of 3 months in Japan and then to visit China on our return journey. Kindly advise and guide.