There are six grand sumo tournaments (basho) throughout the year in Japan.
Tokyo - January, May & September
at the Ryogoku Kokugikan Sports Stadium
Osaka - March
Nagoya - July
Fukuoka - November.
Images of Sumo
Read Will Yong at a Sumo tournament
Japan Sport: Sumo An Overview
"A Day in the Life of a Sumo Wrestler"
Sumo Wrestling - an Overview"