I had some more "Sumo" experiences that I would like to mention.
Some days after the Sumo chankokai party, I received a nice present from them consisting of a piece of good Japanese paper with my name written on it in Kanji (it reads "Dani") by a master of Japanese calligraphy (shodou 書道)
Some weeks later I attended another interesting event called Nagoya Rave 2009. During the event, which was near Nagoya Castle, there were lots of Sumo amateur fights, including foreign wrestlers that wanted to experience this Japanese sport.
Finally, some weeks later I attended a professional event, the grand sumo tournament where I took the video above. The Sumo stadium, called Nagoya Basho and very close to the castle, was full of people. I liked the fights very much and also the traditional rituals that were involved.
I had the luck to be guided by volunteer members of the AGGN (Aichi Goodwill Guides Network). They explained me the situation of the tournament, the names and characteristics of the wrestlers or details about the ceremony. Thank you very much for your help! :)