In a land area of 9,044 square kilometers, the diocesan territory covers Kagoshima prefecture.
As of the end of 2016, the population in the diocesan area was 1,646,757. Most of them are ethnic Japanese. There are also 5,713 non-Japanese people, according to the Immigration Bureau of Japan.
The territory also has many languages/dialects.
The Prefecture Apostolic of Kagoshima was established on March 18, 1927 when the two prefectures of Kagoshima and Okinawa were separated from the Nagasaki Diocese and entrusted to Canadian Franciscans. The first Administrator Apostolic was Monsignor Egide Roy, O.F.M. Upon his resignation in 1936, Father Aijiro Yamaguchi was appointed as his successor, and from the following year he was concomitantly Bishop of Nagasaki. In 1940 Father Ichitaro Ideguchi was appointed Prefect Apostolic.
After World War II, Okinawa and the Southwest Islands came under American military occupation and were entrusted to American Capuchin Friars. Afterwards, when the Southwest Islands (Amamioshima Region) were returned to Japan, they were reunited to the Prefecture Apostolic of Kagoshima.
On Feb. 25, 1955, the Prefecture Apostolic of Kagoshima was elevated to the status of a diocese, and Monsignor Asajiro Satowaki was appointed the first Bishop of Kagoshima. He was consecrated on May 3, 1955.
On Dec. 19, 1968 Bishop Satowaki was appointed Archbishop of Nagasaki and on Nov. 15, 1969 Father Shin'ichi Itonaga was appointed his successor in Kagoshima. He was consecrated Bishop on Jan. 18, 1970 and took office as Bishop of Kagoshima.
Father Kenjiro Koriyama was appointed the successor of Bishop Itonaga on Dec. 3, 2005 and consecrated Bishop of Kagoshima on Jan. 29, 2006. (Catholic Bishops' Conference of Japan, 2010)
Airplanes, railways, buses and ships are modes of transportation in the diocesan area.
Throughout Japan, literacy is 99 percent as the Central Intelligence Agency, USA, reports in 2010.