Question. Do I need a visa? Or do i qualify for free transit?

I will be traveling from LA to Shanghai but have 1.5 hour stopover in xiamen with a connecting flight which i will not be leaving the airport. All under 24 hours in mainland. I will be staying in Shanghai for 3 days then traveling to Hong Kong 3 days , then Tokyo 4 days. From Tokyo I will return to Shanghai and leave within 3 hours back to LA. In my flight back to LA I will have another layover for 2.5 hours with a connecting flight in Xiamen to LA but will not be leaving the area. In returning back to La this will be all under 24 hours in mainland.