Professional sumo as administered by the Japan Sumo Association is divided into six ranked divisions. Wrestlers are promoted and demoted within and between these divisions based on the merit of their win–loss records in official tournaments. For more information see kachi-koshi and make-koshi. Wrestlers are also ranked within each division. The higher a wrestler's rank within a division is, the stronger the general level of opponents he will have to face becomes. According to tradition, each rank is further subdivided into East and West, with East being slightly more prestigious, and ranked slightly higher than its West counterpart. The divisions, ranked in order of hierarchy from highest to lowest, are as follows:

Sumo is a form of competitive full-contact wrestling where a rikishi (wrestler) attempts to force his opponent out of a circular ring (dohyō) or into touching the ground with any body part other than the soles of his feet.