Transit G Required for SIN-PEK-TOK and return?

I hold Malaysian passport.
I'm flying China airline from Singapore to Tokyo (via Beijing).
My SIN-PEK-TOK has a short layover (2hrs).
But TOK-PEK-SIN has a 14hour layover.
Question - is it possible to come out and tour the city during the 14-hour period? How to do that (what entry permit etc)?
Rgds
TL