Japanese gun

The Gongna Beach defenses are a collection of World War II structures built on or near Gongna Beach in Tamuning on the island of Guam, now a United States territory. These defenses were erected by the Imperial Japanese Army during its occupation of the island 1941–44. The three surviving elements were listed on the National Register of Historic Places in 1991. They are located well north of the main Allied landing areas of the 1944 Battle of Guam.

Source: Wikipedia