The win takes the Czechs to 1-1 and still gives them a chance to advance to the playoff round while Japan is in dire straits with an 0-2 record.
Both teams have the day off tomorrow, but on Wednesday the Japanese have a critical game against Switzerland. The Czechs and Finns also play that day.
Natalie Mlynkova got the only goal of the first period, one in which the Czechs also had to kill the only two penalties. In the second, more penalties gave the Japanese the opportunity they needed, and on their fourth power play of the game captain Akane Shiga tied the score.
The Czechs were relentless, though, and scored twice more before the end of the period. Hana Haasova put them ahead again just 82 seconds after Shiga’s goal, and then Mlynkova got her second of the game just before the end when her screen shot fooled Reika Sasaki.
The hosts made it close again on an Ami Sasaki goal early in the third, but Sara Cajanova put the game out of reach on a superb goal at 18:31, dashing the length of the ice before beating Sasaki.