Wool can be said to be the ultimate natural material with the best function among natural fibers, synthetic fibers and various fibers. The fluffy sheep's appearance consists of a collection of curly hair called crimps, which creates a layer of air and acts as a heat insulating material. This is an excellent material that blocks the heat and cold of the outside air. The surface of each fiber closes the scale-like scale to maintain humidity and store body temperature. When it is hot and humid, the scale opens to release heat and lower the body temperature. The function of the wool is superior to any artificial fiber that is being developed and advanced. However, such scales also have their disadvantages: when they get wet, they start to open, and the friction between them causes them to become entangled and become untidy. That is what is called feltization. That was one of the biggest drawbacks of using wool for clothing, and knitwear and jackets had to always be dry cleaned. As a result of the research to solve it, "Washable wool" has appeared. This uses chlorine to melt the wool scale. If there is no entanglement between scales, it will not be felt. However, losing the scale leads to losing the original function of wool. In addition, there are major environmental problems associated with the use of chlorine, which is a harmful substance. The wool's theory that "you can't wash without a scale". That it was overturned the common sense Sato fiber Co., Ltd. has developed WAPRIL processing. It is a dreamlike technology that maintains the function of wool by leaving the scale intact while achieving washable without using harmful substances. RaYS as a material for innerwear that maximizes the function of woolDeveloped. RaYS is a yarn made from WAFIL processing of super fine merino wool, which has a softness that exceeds that of extra fine merino wool, which is generally treated as a high-class item. This wool does not squeeze or tingle when worn on bare skin. The ultimate material that allows you to spend all season comfortably by being able to wash while fully utilizing the function of wool has been born.