It refers to a tile with scratch scratches.
It has nothing to do with a cat's nail.
It became popular after the main building of the Imperial Hotel was completed. The downside of tiles is that several percent of the manufacturing process are burned out and cannot be commercialized.
However, the tiles in the photo (scratch tiles) are rather wonderful because the unevenness is out. For economic reasons, I think it was widely used after the Great Kanto Earthquake.
You can see it in the Suzuki Building next to the Chuo-ku government office and the Daiichi Sugawara Building in front of Ginza Toyo Iwaine cargo. If you look at it carefully, you will find it interesting.
