Instant tatami on the lawns of the parks in spring, summer grains umbrella in search of cool, autumn screen, cozy winter coat for bare trees … .. nailed, encordée, pegged, or floating encollée everywhere in the city as in the countryside, a beautiful blue enamel landscape of the Japanese archipelago. The Japanese call it Ao Ba, "the blue sheet." A nice name for a simple sheet, a square of plastic manufactured in series with a modest but very useful function to protect and isolate surfaces and objects in a country where typhoons and earthquakes are so frequent that hailstorm.