The idea behind tariffs is to move the prices up so that local or other area products are the same cost. And it also brings in more money to the government pile of course. So China would be selling less now since we would just move to purchasing products from other areas with better quality. If a Japanese made item cost the same as a Chinese one, what would you get?
China puts so much extra cost on goods imported that many low or mid line products in the US are considered luxury in China since the cost is so much higher and they are more rare.