With Japan facing powerhouse Scotland in a match that could see them advance past the group stage for the first time, high ratings were expected. The match achieved the highest ratings of any program broadcast this year.
The Kansai region recorded 37.2%, and the Nagoya region recorded 39.1%, both high ratings.
The peak instantaneous rating of 53.7% (Kanto region) was recorded at 9:41 PM when Japan secured its place in the quarterfinals. Ratings also exceeded 50% in both the Kansai and Nagoya regions.
Ratings for Japan's matches have been steadily climbing since the tournament began.
Japan will face South Africa in the quarterfinals on the 20th.
NHK had initially planned to broadcast the match on BS, but has decided to air it live on its main channel instead.