The article introduces a new way to measure how efficiently Japan uses energy. The researchers studied data from 1973 to 2006 and found issues with the old method of calculating energy intensity in the country. They discovered that the previous method didn't accurately reflect actual energy usage, showing higher figures before the mid-1980s and lower ones after. From 1991 to 2001, energy intensity in Japan increased notably, mainly due to rises in energy usage in manufacturing and energy sectors. The study highlights the importance of accurately measuring energy intensity to develop effective energy policies and conserve resources.