U.S. to Japan to Beijing to U.S. - qualifies?

I am a U.S. citizen. In a few weeks, I will fly from SF to Tokyo and then on to BJ. I plan to tour around BJ for five days, and then fly back to the U.S. Will I qualify for the 144-hour transit visa? I'm fine on time and I've booked a hotel in BJ, but does my itinerary count as transit via a third country since my origin is the U.S. and my return destination is the U.S.? I am just transiting to a new flight in Tokyo (four-hour airport layover), but technically, my arrival into China will be from Japan, not the U.S.