Police raided the Onomatsu and other sumo stables Wednesday to look for evidence of illegal gambling, and dozens of other places are expected to also be searched before Sunday's start of the Nagoya grand tournament.
The searches represent a big step in building cases against the active and former sumo wrestlers implicated, and follow the Japan Sumo Association's expulsion last Sunday of top-division ozeki Kotomitsuki and stablemaster Otake for gambling on professional baseball games.
The Onomatsu stable, in Narashino, Chiba Prefecture, is suspected of having played a central role in the wrestlers' gambling, allegedly run by a bookie linked to mobsters. Kotomitsuki and Otake are believed to have repeatedly gambled through the stable.