Hi! I got a multicity journey that i booked with Air China (one-way tickets)

I have already booked a journey with Air China,

16th march from Stockholm, Sweden and arriving to Beijing on the 17th (one-way ticket)
My next flight is on the 19th march. Beijing to Tokyo, Japan (one-way ticket)

In this case, I can use the 72h exemption that are available at the airport?
It is also true that I have to collect my luggage after I arrived? For I did bought a one way ticket to Beijing.

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On my way home from Japan via Beijing to Sweden, can i re-entry the country again and use the 72h exemption after just 10 days?