Japan's first civil air raid drills were held in Osaka in 1928, but it wasn't until March 1937 that the Diet passed an Air Defense Act establishing rules on how things should work in the event of bombing raids on the homeland. War in China was imminent, but few probably could have imagined the horror of the air raids to come the following decade.
With Japan-U.S. relations growing tense, in February 1941 the law was amended in two important respects. First, the government was empowered to prohibit civilians from seeking safety — to order them to remain in areas likely to be bombed. Second, owners and occupants of houses and buildings became legally obligated to help fight fires caused by air raids. These mandates were backed by stiff criminal penalties.
The real enforcement, however, came through the Home Ministry's oppressive tonarigumi system of local organization and mutual supervision (remnants of which survive today in the form of chōnaikai community associations). Since wartime rationing was conducted through these organizations, compliance could be achieved through the tacit threat of further hunger and deprivation.