In a land area of 18,792 square kilometers, the diocesan territory covers Kagawa, Ehime, Tokushimaand Kochiprefectures.
In the diocesan territory, the population is 3,845,000 at end of 2017. Most residents are ethnic Japanese. There are also 27,613 non-Japanese people according to the Immigration Bureau of Japan.
The territory also has many languages/dialects.
The Prefecture Apostolic of Shikoku was established on January 27, 1904 when the four prefectures of Shikoku (Tokushima, Kochi, Kagawa, and Ehime) were separated from the Diocese of Osaka and entrusted to Spanish Dominicans of the Rosario Province. On February 26, 1904, Father Jose Alvarez, O.P. was appointed as the first prefect apostolic.
In 1931, when Monsignor Alvarez resigned because of illness, Monsignor Tomas de la Hoz, O.P. succeeded him as prefect apostolic. In 1935 Father Modesto Perez, O.P. was appointed. He resigned in 1940, and from 1941 Bishop Yoshigoro Taguchi of Osaka served concomitantly as administrator of the Prefecture Apostolic of Shikoku. In 1949, the prefect apostolic's residence was moved from Tokushima to Takamatsu.
On September 13, 1963, the Prefecture Apostolic of Shikoku was elevated to the status of a diocese and its name was changed to the Diocese of Takamatsu. On October 20 of that year Father Eikichi Tanaka was consecrated bishop and became the first Bishop of Takamatsu. Father Satoshi Fukahori was consecrated bishop on September 23, 1977 and took over as Bishop of Takamatsu.
On May 14, 2004, Bishop Fukahori resigned and Bishop Osamu Mizobe was appointed his successor. Bishop Mizobe was installed on July 19, 2004. (Catholic Bishops' Conference of Japan, 2010)
Airplanes, railways, ships and buses are modes of transportation in the diocesan territory
Throughout Japan, literacy is 99 percent according to the Central Intelligence Agency, USA, in 2010.