May 9th, 2018. Sumo Training Hall, Asahi University, Mizuho Gifu, Japan. A male and a female member of the Asahi University Sumo Club sweep the surface of the dohyo, the sumo ring, at the end of a training session. The dohyo is a circle shaped ring made of a special kind of clay, covered with a thin layer of sand which makes it smooth enough to enable the sumotori’s feet to slide. Its borders are marked by half-buried rice straw. In professional sumo, the dohyo is blessed by a shinto priest before tournaments and sprinkled with salt after each bout. In professional sumo, women are not allowed to touch the dohyo because they are considered impure by Shinto religion.