Established in 1934 with Mitsui Trading Company, Tokunaga Sheet Glass Manufacturing Company began producing sheet glass in 1938 just when the glass market started to go down in the war economy. In November 1940, Tokunaga’s negotiation with Sumitomo Company was concluded at the signing of merger agreement between Tokunaga and Nippon Sheet Glass. Gaining Tokunaga’s factory in Amagasaki and adding their template and wired glass to the product lineup, the merger helped expand the operation of Nippon Sheet Glass.