The Kumaya family were prosperous and wealthy merchants engaged in wholesaling, finance, stock brokerage, and salt production, and they were the official purveyors of the Hagi domain. The Kumaya Family Residence is believed to have been built in 1768. Four of its buildings have been designated as national important cultural properties: the main house, the detached house, the main storehouse, and the treasury.

Kumaya Art Gallery opened in April 1965 in order to preserve and display cultural artifacts. Works of art collected by the various heads of the Kumaya family are displayed in an exhibition room that was converted from a storehouse of the Kumaya family, who were the official purveyors of the Hagi domain. The collection includes approximately 3,000 items, including calligraphic works, paintings, folding screens by Sesshu and other artists, tea ceremony utensils, handcrafts such as incense burners and inkstone cases, and documents handed down from one generation to the next.

One of the most eye-catching items in the collection is a piano given to Goemon Yoshikazu, the fourth-generation head of the family, by Siebold, a German doctor and close friend from his time in Nagasaki. This piano, made in England is famous for being the oldest remaining piano in Japan.