USA > Shanghai (layover) > Beijing

Hey Im looking at a flight from USA to Beijing with a layover in Shanghai. My intentions are to use the flight to visit the layover city, Shanghai, without continuing the final leg to Beijing. And from Shanghai catch a flight out to Japan. My question is will the airline still allow me to board if they know im skipping the final leg with a prebooked ticket out of Shanghai to Japan, under the 144 hr transit visa?