Jōtō-ku is one of the 24 wards of Osaka, Japan. "Jōtō" means "east of the castle", referring to Osaka Castle. It was separated from Higashinari and Asahi in 1943, and eastern Jōtō became Tsurumi in 1974. Jōtō-ku has the highest population density of any ward in a city-designated municipality in Japan, and is the only ward with a density that exceeds 20,000 people per square kilometre.