Round Trip Ticket To Shanghai but Japan in between

Hi
I need help answering some questions regarding the visa requirement:

I have a Canadian passport. I purchased a round trip ticket from Toronto to Shanghai from May 7 to 29th, and also roundtrip ticket from Shanghai to Japan from May 9 - 24 with a different airline. So I will be in Shanghai from May 8- 9, then May 25 - 29. The total amount of time I will be spending in Shanghai is 126 hours, and will be staying in Shanghai for less than 24 hours when I first arrive. Am I eligible under the 144 hour free transit? Would I have to apply for the 144 hr free transit both times I enter or just the second time?

Thanks!