I land In PEK T3 and depart from T3, do I have to go through of customs, immigration, & quarantine?

I am flying from London to Tokyo. London (country A) - Beijing PEK ( Country B) - Tokyo ( country C). I will land in T3 and catch my connecting flight in T3 to Tokyo. With a layover time of 1 hour and 50 minutes in T3, staying at the airport. Do I still have to go through customs, immigration, security & quarantine ? Before catching my connecting flight. Or do I just catch my next flight, without going through customs, immigration, security & quarantine?