NHK transmitted "China Buys Japan" as part of its Inside Lens series.
It followed a small tour group in the first week of October 2015 (a particularly busy period as it coincides with a major Chinese holiday. The program makers also chatted with a few store owners. Made interesting viewing and it's currently still available:
http://www3.nhk.or.jp/nhkworld/en/vo.../20160125.html
I was in Seoul last October with plenty of time on my hands and a modest amount in my pocket yet found it extremely difficult to do any meaningful shopping - with the exception of some children's clothes (loved the GoDeLaBon brand) and a few food items. The airside part of ICN airport in particular had literally nothing to offer me (had received a text from one of my husband's colleagues warning that there was nothing to buy, was surprised to realise he was right). This is not a problem I've ever had in Japan. The only reason we got to return home with a Turning Mecard transforming car for our amazed and overjoyed daughter was because it was presented to us as a gift for her by my husband's Korean hosts. Shame I only learned about it once we were back in the UK, but apparently they're (or at least they were) a b*gger to find in the stores.
I'd previously wondered why so many ordinary Chinese people chose to do their shopping in Tokyo rather than in Seoul, which is cheaper. Now I get it.