Japan (Mima Ito/Jun Mizutani) knocked off top-seeded China (Xin Xu/Shiwen Liu) in seven games to win the first-ever mixed doubles gold medal. #NBCOlympics #Tokyo2020 #TableTennis » Subscribe to NBC Sports: https://www.youtube.com/nbcsports?sub_confirmation=1 » Watch live Olympic coverage on NBCOlympics.com: https://www.nbcolympics.com/schedule NBC…