A day for the humble, yet essential blue sheet

There is even a day dedicated to blue sheets in Japan. It is called Sheet Day シートの日 and it is on April 10th annually. I can't even begin to explain the position of blue sheets in Japan. They are so widely used in Japan, more than any other sheet or covering, that you wonder how you ever survived without a blue sheet before you moved to Japan!

The date of the anniversary comes from simple wordplay: 4/10 can be read as "shi- (4) to (10)", the Japanese for sheet. The purpose behind the anniversary is practical: to highlight the importance of blue sheets in everyday life and in emergency situations. From construction sites and school sports days to picnics, gardening and disaster relief, these lightweight waterproof sheets quietly support countless moments across Japan. 

Blue sheets themselves have an interesting history. When Hagiwara Industry first released them in 1965, they were marketed as a versatile waterproof cover. At the time, orange was the standard color, but blue eventually took over. Several explanations exist; blue pigment was inexpensive, the color felt clean and refreshing, and it echoed the sky and sea. Over time, “blue sheet” became the universal name for all polyethylene tarps in Japan.