On December 7, 1944, Japan’s southeast coast was hit by a huge earthquake (M 7.9), leaving 1,183 dead or missing and more than 20,000 buildings completely destroyed. At the Yokkaichi Plant, three chimneys collapsed and the foundations of the melting tank, annealing kiln and steam turbine all suffered extensive damage, totally shuttering the production facility.
In response to a strong request from the military, the plant managed to resume production of polished plate glass in January of the following year, only to be destroyed again by air raid. The war finally ended in August 1945 but the Yokkaichi Plant was hit by another earthquake (M 8.0) on December 21, 1946 which left 1,443 dead or missing. Despite a string of disasters, the Yokkaichi Plant went back into operation.