It's quite possible there is a world shortage of "sumo fiction" everywhere. The lack is almost so pervasive, I would guess, that most readers barely notice the lack.
BUT NEVER FEAR! Coming soon (as in Fall 2012 soon) to a bookstore to you: Big in Japan, the world's first novel with a sumo wrestler as the main-character/love-interest, a BLOND sumo wrestler, at that.
I am happy to announce that my long, long worked-upon novel has been selected for publication by Jolly Fish Press, and it will be in their publication list next fall. Big in Japan tells the story of an overweight nobody from Texas who ends up in Japan and accidentally becomes the world's first blond sumo wrestler. He must face down his biggest enemy and win the Emperor's Cup to save the girl, the "princess" of sumo.
Is the world ready for a sumo wrestler novel? Hang onto your mawashi, folks. It's coming at ya!