Shimane Prefecture Yamaguchi Prefecture Hagi has a humid subtropical climate (Köppen Cfa) with hot, humid and wet summers combined with cool to mild winters, with a relatively high precipitation amount compared to mainland Asian locations on similar latitudes.

During the Muromachi period, the Yoshimi clan built a minor fortification at a fishing village where the city is now located.

During the Edo Period, the area was the center of Chōshū Domain, with the Mōri clan ruling as daimyō from their stronghold at Hagi Castle for 250 years.

The town of Hagi within Abu District, Yamaguchi was established on April 1, 1889 with the creation of the modern municipalities system.

Hagi has a mayor-council form of government with a directly elected mayor and a unicameral city council of 20 members.

In terms of national politics, the city is part of the Yamaguchi 3rd district of the lower house of the Diet of Japan.

Hagi is home to the Ground Self-Defense Force's Mutsumi Training Area, and is a proposed installation site for the Aegis Ashore missile defense system.