The following is an alphabetical list of heya or training stables in professional sumo. Each belongs to one of six groups, called ichimon. These groups, led by the stable by which each group is named, are in order of size: Dewanoumi ichimon, Nishinoseki ichimon, Tokitsukaze ichimon, Takasago ichimon, Isegahama ichimon, and the splinter group led by Takanohana stable that broke off in February 2010 but was subsequently given ichimon status in 2014; see here. The founding dates listed below are for the current incarnation of each stable; in most cases this is not the first stable to exist under a given name, however.
The number of stables peaked at 54, with the opening of Onoe stable in August 2006. In order to limit the over-proliferation of stable the Japan Sumo Association introduced new rules the following month that greatly raised the qualifications needed by former wrestlers wishing to branch out (namely, those ranked below yokozuna or ōzeki must have spent at least 60 tournaments in the top makuuchi division or 25 in the titled san'yaku ranks). Discounting the special circumstances of the temporary closure of Kise stable from 2010 until 2012, there were no new stables established for more than six years, while eleven folded, bringing the number of active heya down to 43. This sequence was ended by the opening of former yokozuna Musashimaru's Musashigawa stable in April 2013. Since this time the opening and closing of stables has stabilized and the number of stables has remained in the mid 40s.
Due to a Japanese speech phenomenon known as rendaku, when the word for stable, heya, comes second in a compound word, the "h" in heya changes to "b" to become beya. A sumo stable is pronounced in Japanese as "sumo-beya" and Arashio stable, as an example, is pronounced "Arashio-beya".
There are 44 stables as of January 2017.
Recent mergers and closures
Kasugayama stable closes October 2016, some wrestlers retire, other wrestlers and personnel move to Oitekaze stable
Asahiyama stable closes January 2015, all wrestlers and some personnel move to Isegahama, some other personnel move to Asakayama.
Mihogaseki stable closes October 2013, wrestlers move to Kasugano
Magaki stable closes March 2013, wrestlers move to Isegahama
Hanaregoma stable closes February 2013, wrestlers move to Shibatayama
Nishonoseki stable closes January 2013, remaining wrestlers retire, other personnel move to Matsugane
Nakamura stable closes December 2012, wrestlers move to Azumazeki
Hanakago stable closes May 2012, wrestlers move to Minezaki
Ōshima stable closes April 2012, wrestlers move to Tomozuna
Tagonoura stable closes February 2012, wrestlers move to Dewanoumi and Kasugano
Takashima stable closes June 2011, head coach moves to Kasugayama
Kiriyama stable closes January 2011, wrestlers move to Asahiyama
Araiso stable closes September 2008, one remaining wrestler moves to Hanakago
Isegahama stable closes February 2007, wrestlers move to Kiriyama
Hatachiyama stable closes June 2006, wrestlers move to Kitanoumi
Oshiogawa stable closes March 2005, wrestlers move to Oguruma
Takekuma stable closes March 2004, no wrestlers are left but head coach moves to Tomozuna
Kabutoyama stable closes December 2002, no wrestlers are left but head coach moves to Minato
Wakamatsu stable merges with Takasago in February 2002
Tatsutagawa stable closes November 2000, wrestlers move to Michinoku
Kise stable closes February 2000, wrestlers move to Kiriyama
Kumagatani stable closes April 1996, wrestlers move to Tatsunami
Ōnaruto stable closes December 1994, wrestlers move to Kiriyama
Kitanoumi stable is renamed Yamahibiki stable in November 2015
Matsugane stable is renamed Nishonoseki stable in December 2014.
Naruto stable is renamed Tagonoura stable in December 2013.
Musashigawa stable is renamed Fujishima stable in September 2010.
Ajigawa stable is renamed Isegahama stable in November 2007.
Futagoyama stable is renamed Takanohana stable in February 2004.
Taihō stable is renamed Ōtake stable in February 2003.
Nakadachi stable is renamed Sakaigawa stable in January 2003.
