Sumo is a Japanese form of wrestling. There are tree different types of sumowrestlers: oshi-zumo, yotsu-zumo and namakura-yotsu. Oshi-zumo prefers fighting apart. This type is generally heavier wrestlers with great power and momentum. The yotsu-zumo is more technical and prefers to shove one arm inside the others arm. Namakura-yotsu is a wrestler that has no strong preference for either style.

The earliest recordings of Sumo was in 469 AD in mythical literatures of Kojiki and Nihon-Shoki. The time limit system for rikishi (wrestlers) to prepare for a bout started in 1928 with the start of radio broadcasting. Before that the time limit for Makuuchi were 10 minutes, for the Juuryou 7 minutes and for the Makushita 5 minutes.