Japanese leaders certainly expected civilians to take part in the final defense of the Japanese mainland. On 23 March 1945, the cabinet authorized the creation of the People's Volunteer Corps (Kokumin giyūtai), which would allow civilian volunteers (under military command) to engage in war-related duties like firefighting, fortification construction, and food production. On 14 June, however, service in the "Volunteer" Corps became mandatory for all men from the ages of 16 to 61 (or 15 to 65 for actual volunteers) and all women from the ages of 17 to 40 (up to 45 for volunteers). Not long afterwards, on 23 June, the military began to organize a People's Volunteer Fighting Corps (Kokumin giyū sentōtai); in fact, the People's Volunteer Corps was to be converted into a combat force too when the Americans finally invaded.

These civilians, who received only limited military training, would attempt to fight the enemy with primitive or improvised weapons, knowing that they themselves would probably die in the process. As Edward Drea relates in his essay on Japanese defense preparations in 1945:

A few months ago, I contacted my professor in Tokyo, who was sixteen years old in 1945 and well remembered the People's Volunteer Corps---he was in it. His "equipment" consisted of a bamboo spear and a backpack filled with two large stones. He practiced huddling in a dank, stinking, foxhole, waiting for the Americans. If the enemy approached, he would exchange his stones for a land mine. His mission was to destroy an enemy tank, and himself, with it. Reflecting back, the training, indeed the whole notion, was similar to something out of a demented cartoon. But, he emphasized, the military was serious. And if the Americans landed, he is certain he would have perished.

Araki Shigeko, the widow of kamikaze pilot, likewise recalled how she and her fellow factory-workers would drill each day with bamboo spears:

We were going to do it with our bamboo spears. When they landed we would attack them. We had those spears at our right hand at all times at the factory. "Each one, stab one, without fail!" they'd tell us. "Yes!" we'd reply in unison.

Our spear was about a meter and a half long, with a sharp point cut diagonally across at the end. We practiced every morning, "Thrust! Thrust! Thrust!" I thought I'd definitely be able to stab them. We had the image of the Americans as being gigantic. We were told, "Americans are large and well built, so go for the throat. Stab here, drive your spear up into the throat. Don't look at the face. Stab without looking." We really believed we could do it. Isn't it scary? We often called this "Yamato damashii," the "Spirit of Japan." We'd put on our headband with the rising sun emblazoned on it. Then we'd bow deeply in the direction of the Imperial Palace. Next, we drilled with our bamboo spears. Finally, we'd start our work. But I enjoyed it. It was for Japan, it was to preserve and protect the country. We were sending our loved ones off to die to protect the country. It was the least we could do on the home front. It's amazing isn't it? Beyond comprehension today. At that time we had an unbounded faith in Japan. We felt the Yamato race was unequaled.

It's worth mention that even the formal military units assigned to the defense of the Japanese mainland included many under-trained, under-equipped, and inexperienced soldiers; in fact, entire divisions would basically function as speed bumps, fighting to the death near beachheads while other forces got into position to counterattack. An invasion of Japan would have proved an utter bloodbath, by all estimates.

Sources:

Akira Fujiwara. Taiheiyō sensō shiron [Historical Essays on the Pacific War]. Tokyo: Aoki shoten, 1982.

Cook, Haruko Taya, and Theodore F. Cook. Japan at War: An Oral History. New York: New Press, 1992.

Drea, Edward. In the Service of the Emperor: Essays on the Imperial Japanese Army. Lincoln: University of Nebraska Press, 1998.

Takeshi Hara, and Akio Yasuoka. Nihon Riku-Kaigun jiten [Encyclopedia of the Japanese Army and Navy]. Tokyo: Shin jinbutsu ōraisha, 2003.