One night, Naoyuki's family watches a disaster prevention anime DVD distributed at school. Even though Bousai Namazun teaches them about the Tokai, Tonankai, and Nankai earthquakes that could strike at any time, the older brother, Naoyuki, can only think, "Is an earthquake really going to happen?"

The next day, a major earthquake occurs while their father and mother are away. Even though they want to go to an evacuation shelter, the furniture throughout the house has fallen over, and the living room door is warped, so they cannot open it by themselves. "What if Mom doesn't come back...?" his younger sister, Sayaka, starts to cry. Is their father, who went to a seaside factory, safe? The two wait anxiously for help. At that moment...

(Source: Official site, translated)