Kumamoto Prefecture Nagasu has a humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall.

Nagasu has a mayor-council form of government with a directly elected mayor and a unicameral town council of 14 members.

Nagasu, collectively with the other municipalities of Tamana District, contributes one member to the Kumamoto Prefectural Assembly.

In terms of national politics, the town is part of the Kumamoto 2nd district of the lower house of the Diet of Japan.

The local economy is based on commercial fishing, aquaculture of edible seaweed and goldfish, and food processing.