People stand around the dohyo (the ring) to make sure no one runs up and steps on it as the national stadium (kokugikan) empties after a day of sumo wrestling.
Sexism, like racism, is everywhere in the world. This is obviously a fact. No society can dictate the thoughts or actions of individuals. What a society can do is make rules and laws in order to reduce the ability for its citizens to act on various prejudices. The presence of those laws and the way in which they are enforced (or ignored) represents the aggregate wishes of the society. In Japan, there are equal employment laws, but they are ignored. In some areas of Japanese culture, there are laws that overtly prohibit women from taking part in various activities even when there is absolutely no reason or rationale behind that prohibition. One example of that is the fact that women aren't allowed to step onto the sumo dohyo to hand over the sumo tournament trophy to the winner. It's understandable that a woman can't take part in sumo wrestling itself because of physical capabilities. It's not understandable that she can't present a trophy because she is considered too "unclean" to step on the dohyo (ring).
I won't miss this type of institutionalized sexism and how it is tolerated.