Even though they are now less common, room size in Japan is still often measured according to the number of tatami mats it can hold, so you might get a six- or eight-tatami mat room. A tatami mat is approximately 90cm x 180cm - it varies according to origin - and is a made up of several layers with a soft woven rush top. The making of tatami mats is still a revered traditional craft; see for example the family company Oee Tatami which is featured in Shokunin (2025), Ben Richards' book about craft workshops in Japan. This is the beautifully preserved 1929 Japanese-style annexe to the former Marquis Maeda Residence in Komaba Park, Tokyo.