In a land area of 11,446 square kilometers, the diocesan territory covers Oita and Miyazaki prefectures.
The total population in the territory is 2,292,454 as of the end of 2016. Most of them are ethnic Japanese. There are also 15,196 non-Japanese people, according to the Immigration Bureau of Japan.
The territory also has many languages/dialects.
On March 28, 1928, the two prefectures of Miyazaki and Oita were separated from the Fukuoka diocese and entrusted to Italian Salesian Fathers. On Jan. 28, 1935, it became the prefecture apostolic of Miyazaki and Father Vincenzo Cimatti, S.D.B., was appointed the first ordinary. In 1940 Monsignor Cimatti resigned, and Monsignor Ichitaro Ideguchi, prefect apostolic of Kagoshima, served concomitantly as administrator apostolic of Miyazaki. From 1946 Bishop Sen'emon Fukahori of Fukuoka served concomitantly as administrator apostolic of Miyazaki.
On Dec. 22, 1961, the prefecture apostolic of Miyazaki was raised to the status of a diocese and became the diocese of Oita. Father Saburo Hirata was appointed the first bishop of Oita and was consecrated on March 26, 1962.
On Nov. 15, 1969, Bishop Hirata was appointed bishop of Fukuoka and Father Takaaki Hirayama was appointed to replace him in Oita. He was consecrated bishop on Jan. 25, 1970.
On June 12, 2000, Bishop Hirayama retired and Nagasaki diocesan priest Father Ryoji Miyahara was appointed as his successor. He was consecrated bishop on Oct. 1, 2000.
Due to Bishop Miyahara being named Bishop of Fukuoka on March 19, 2008, and installed on May 18, 2008, the episcopacy is vacant at this time.
Airplanes, railways, buses and ships are modes of transportation in the region.
Throughout Japan, literacy is 99 percent, according to the Central Intelligence Agency, US report 2010.