There are some sumo stables.
There are some sumo stables that are off limits to normal citizens. Also, at some places, the sumo may be on patrol around town, or the stable may be in quite a remote area. These stables here are apparently open for viewing, but you may need help inquiring with the site:
http://www.kokonoe-beya.com/
http://hakkakubeya.com/
http://www.geocities.jp/sakaigawa_beya/
http://www.azumazeki.jp/
SEIJAN
Japan