The huge building sheltered with reed screens, which can be seen on the right side of the main hall of Ekōin Temple, is a Sumo hall. Drumbeat from the Sumo tower, that stands outside the front gate, announces to the people of Edo the beginning of Kanjin Sumo wrestling matches (fund-raising sumo held in aid of a temple or a shrine).

Ekōin is a temple that was build for the repose of the souls of people who were killed in the Great Fire of Meireki in 1657 (Meireki 3). One of the purposes to visit the temple for many people in Edo, however, was to watch Kanjin Zumō (public sumō bouts).
Kanjin Zumō was held in the precincts of Ekōin Temple for the first time in 1785 (Tenmei 5). Since 1883 (Tempō 4), the matches had been held twice a year in every spring and fall at the temporary sumō hall sheltered with reed screens, which was built in the precincts of the temple and used as a standing venue for Edo Sumō. Around that time, the schedule of Kanjin Zumō was established with four tournaments a year in three cities-in Edo for spring and fall, in Kyoto for summer and in Osaka for fall.
Edo Sumo was held in Ekōin Temple until 1909 (Meiji 42) when the Wrestling Amphitheatre (which was burned down in the Taishō period) was completed.