Japan uses both 50Hz and 60Hz power frequencies due to historical and logistical reasons that date back to the early days of electrification in the country. In the 19th century, early power companies operated locally, leading to the establishment of a dual-frequency system.

Japan’s power grid is divided into two regions: Eastern Japan operates at 50 Hz, while Western Japan operates at 60 Hz. This division originates from the 1880s, when Tokyo imported 50 Hz generators from Germany, while Osaka chose 60 Hz equipment from the United States. //

The Fujigawa River and the southern border of Niigata Prefecture form the boundary between the two frequencies.