Japan ends four-match losing streak
Hendrik Tui scored two tries, while Shota Horie added another as the japanese eased to victory.
Ayumu Goromaru kicked three conversions and three penalties, from as many attempts, which saw the Brave Blossoms get a confidence boosting win just before the Rugby World Cup.
Japan had to make a late change at flyhalf. Kosei Ono pulled out, and was replaced by Harumichi Tatekawa.
Japan never trailed after Tui went over in the 10th minute, following some good work at the breakdown by Hayden Hopgood.
Felipe Berchesi and Goromaru then exchanged penalties, before Horie's try extended Japan's lead.
Goromaru added the extras but Japan failed to build on the score, as they allowed Jeronimo Etcheverry to go over for a well-worked try for the visitors to make it 17-8 at the break.
The second half saw Japan dominate possession and territory.
Goromaru banged over two penalties before Tui crossed for his second try following a superb driving maul in the 65th minute.
Japan had a number of opportunities to add to the score but slippery conditions saw the ball spilled in contact frequently, or passes didn't quite go to hand.
The game finished with Uruguay looking for a consolation try only to be thwarted by a superb cover tackle by Fumiaki Tanaka.
The two sides meet again in Tokyo next Saturday, with Japan set to leave for England on September 1.
