Miyamura National School (now Miya Junior High School)

Miyamura National School (宮村国民学校) was an elementary and higher-elementary school located in Miya village, Higashisonogi District (now the Miya district of Sasebo), Nagasaki Prefecture. "National schools" were created in April 1941, when the National School Order renamed the country's elementary schools with the stated aim of training "imperial subjects"; schooling was bound closely to mobilisation, and labour service, air-raid drills and military training became part of the school day.

Sasebo was a naval port city, home to a naval district and arsenal, and Miya lay not far from the harbour. As the war worsened and air raids became likely, Principal Ikeda Chiaki (池田千秋) conceived a shelter cut into the tuff hillside near the school that could hold the whole student body and allow lessons to continue. Work began on August 29, 1943 and went on until the end of the war on August 15, 1945. During these final years of World War II the school's teachers and students — from 4th grade upward — undertook the excavation themselves. The work was organized with military efficiency: older boys dug with pickaxes, older girls finished surfaces with chisels, and younger children removed rubble.

Ikeda named the cave Mukyūdō (無窮洞). The main chamber is about 5 metres wide and 20 metres deep, with a lectern, stone desks and candle stands carved from the rock, as well as a kitchen, food store, toilets, a water point, an emergency stairway and an alcove for the imperial portraits, so that it could serve as a classroom. Figures for its capacity differ: local Sasebo material generally gives about 600 students, Nagasaki Prefecture's tourism information about 500. The shelter protected the students during the Sasebo Air Raid of June 28–29, 1945, which devastated the city centre.

After the war the national school system was abolished; the school was reorganized and eventually became Miya Junior High School (宮中学校). Mukyūdō is maintained and opened to the public by a local preservation society, and its tool marks and fittings are well preserved. As an air-raid shelter dug by children it is widely used in peace education, and it also shows how, under total war, even elementary pupils were drawn into the system of air defence and labour mobilisation.