Jeremy Noble had four goals for Canda (3-1), which is trying to catch the United States for the best record in the tournament's top division.
Curtis Dickson had three goals and two assists for the Canadians, while Geoff Snider won 11-of-15 faceoffs in the game and Dillon Ward and Brennan Donville combined for nine saves in goal.
Yuji Tadahira, Wataru Tsugu, and Andrew Lay all scored for Japan.
The Americans maintained their perfect 4-0 record in the tournament with a 20-1 victory over England (0-4).
After a roughly two-hour delay for lightning, the Iroquois Nationals pulled out a 12-10 win over Australia (2-2) to move into a tie with Canada for second place.
The game was tied 8-8 when it was stopped for lightning with 2:39 left in the third quarter.
Germany, Israel, New Zealand and Scotland advanced to the bracket round of the tournament with wins. Three first-time participants China, Thailand and Uganda also picked up their first victories in international competition.
Other results included Scotland 9, Finland 6; Germany 9, Czech Republic 5; Israel 18, Ireland 9; New Zealand 14, Netherlands 10; Uganda 10, Korea 9; China 9, Argentina 7; Thailand 12, Colombia 3; Poland 14, Hong Kong 4; Belgium 18, Costa Rica 4; Latvia 21, Spain 3; Wales 16, Italy 7; Slovakia 17, France 6; Norway 14, Russia 7; Sweden 19, Bermuda 4; Turkey 7, Austria 2 and Switzerland 12, Mexico 3.