japan has etiquette about "tatamiberi". japanese are taught not to step on the "tatamiberi". it is easy to tear "tatamiberi" when stepping in the weakest part. stepping on "tatamiberi" fades the color on the edge of cotton and hemp in the "tatami". therefore etiquette means "not to hurt the mat carelessy stepping when you visit another house, pay it attention". also, family crests were embroidered on the "tatamiberi" in old times, too. stepping on the family crest was taboo.