It is true that the pollution is China is fucking filthily. China has literally _ZERO_ enforcement on their environmental laws - and that is exploited all the time by foreign investors. And due to some minor technicality with the UN, they don't have to follow those regulations either. (Not sure what it is, I used to know...)
How that has anything to do with Japan I am unsure. For the record, China, as a country _HATES Japan.