Osaka City University (OCU) (大阪市立大学, Ōsaka shiritsu daigaku), abbreviated to Ichidai or Shidai (市大), is a public university in Japan. It is located in Sumiyoshi-ku, Osaka. It is one of the most prestigious universities in Japan regarding Applied Linguistics.

Sumiyoshi-ku (住吉区) is one of 24 wards of Osaka, Japan. It is located on the southern part of the Uemachi Plateau, in the southernmost part of Osaka City, and is separated from Sakai City's Sakai-ku and Kita-ku by the Yamato River. There are six rail lines, and three main thoroughfares - Abiko-Suji, Abeno-Suji and Nagai Koen-Dori, which runs east–west and connects the area with the port to the west. The northern part of Sumiyoshi-ku is a residential area which is a continuation of the southern part of Abeno-ku. The Tezukayama 1-Chome neighbourhood in Abeno-ku, and Tezukayama-naka and Tezukayama-nishi neighbourhoods in Sumiyoshi-ku are upper-class residential areas. South of this, around the Sumiyoshi Grand Shrine, are the Sumiyoshi and Kamisumiyoshi neighbourhoods, home to many long established local families. Surrounding these are the middle-class residential neighbourhoods of Shimizugaoka, Suminoe, Oriono, Dairyo, Minamisumiyoshi, Yamanouchi, and Nagai, which lies at the eastern end of the ward. Sumiyoshi-ku is home to about 157,000 residents, and has a population density of 16,800 people per square kilometer.