Mukyudo was a large air raid shelter built by the teachers and students of Miyamura Elementary School (now Miya Junior High School) during World War II. Back then, students that were grade 4 or older used pickaxes to help dig a tunnel into the hillside behind their school, and the construction continued from August 1943 to August 1945. The large air raid shelter was said to be able to accommodate up to 500 students. In addition to being a shelter, it also has dug out toilets, a small kitchen area, a food storage area, and an open space area for classes. The air raid shelter was built with the intension that students can also live inside it while they continue their schooling during the war.
Today, Mukyudo is open to public and the it is still very well preserved.