Marcellino Daiji Tani

Daiji Tani was born on 13 February 1953 in Takarazuka, in Hyogo Prefecture in western Japan. Marcellino was his baptismal name, and as a bishop he was known as Marcellino Tani. His given name is read Daiji in Japanese sources, while some Western directories romanise it as Taiji.

He entered the Interdiocesan Major Seminary of Tokyo and studied philosophy and theology at Sophia University, the Jesuit university in Tokyo, before ordination for the Diocese of Urawa, which covered Saitama and three neighbouring prefectures north of Tokyo.

Tani was ordained a priest on 21 March 1986. According to Catholic Japan News, he served the same year as assistant priest in Urawa, became parish priest of Ageo in 1987, head of the diocesan chancery in 1992, parish priest of Kawaguchi in 1993 and parish priest of Tatebayashi in Gunma Prefecture in 1997. The Holy See's announcement of his appointment as bishop listed him as chancellor of the diocese and parish priest of Tatebayashi.

On 10 May 2000 Pope John Paul II appointed Tani bishop of Urawa. He succeeded Peter Takeo Okada, who had been made Archbishop of Tokyo, and was the sixth bishop of the diocese. Okada consecrated him on 15 September 2000 in the gymnasium of Utsunomiya Kaisei Girls' School in Tochigi Prefecture. The diocese, which covered Saitama, Gunma, Tochigi and Ibaraki prefectures, was renamed the Diocese of Saitama on 31 March 2003 after the creation of Saitama City.

During his thirteen years in charge he promoted pastoral care for foreign Catholics, migrants and refugees and a multicultural church. He chaired the Japanese bishops' Commission for Refugees, Migrants and People on the Move, served as president of the Japan Catholic Council for Justice and Peace and held senior posts on the bishops' committee on buraku discrimination. In January 2011 he accepted John Stephen Kato, a married former Anglican priest who had become a Catholic, into the diocese on condition that he would not lead a parish, and ordained him on 11 February 2011, which UCA News described as the Catholic Church in Japan's first conversion of an Anglican priest.

After the Great East Japan Earthquake of March 2011 he set up the Saitama diocesan support centre to help people in the disaster areas.

Pope Francis accepted his resignation as diocesan bishop on 27 July 2013. No reason was made public. Archbishop Okada of Tokyo became apostolic administrator, and Mario Michiaki Yamanouchi was later appointed bishop of Saitama.

After stepping down Tani moved to Okinawa. In the Diocese of Naha he took charge of the diocesan peace committee, continued pastoral work and led retreats. According to Kirishin, he confronted the issues of the United States military bases and the history of the Battle of Okinawa, and took part in protests against the construction of the new base at Henoko. Catholic Japan News said his work there focused on peace and human rights.

He later moved back to Saitama Prefecture for cancer treatment but kept his interest in Okinawa. In June 2026 he gave an interview to Catholic media in which he reflected on how his years in Okinawa had opened his eyes to a history of discrimination and oppression, and spoke of a faith that walks with people who suffer. His books include Ijusha to tomo ni ikiru kyokai (The church living with migrants, Joshi Paulo-kai, 2008) and a book on the Bible and addiction.

Marcellino Daiji Tani died at 9:41 am on 10 October 2026 at Saitama Red Cross Hospital in Saitama City, aged 73. He had been ill and under treatment for some time, and had moved back to Saitama for cancer treatment; no formal cause of death was announced.

The Catholic Bishops' Conference of Japan announced his death on 13 October 2026 and asked for prayers for his eternal rest. His vigil was held on 16 October and his funeral Mass on 17 October 2026 at the Catholic Urawa Church, the cathedral of the Diocese of Saitama, celebrated by Bishop Mario Michiaki Yamanouchi. In keeping with his wishes, flowers and condolence gifts were declined.

Tani is remembered as a bishop who placed foreign residents, refugees and the socially vulnerable at the centre of the church's mission in Japan. Kirishin's obituary headline summed him up as a bishop who devoted himself to refugee support and the peace movement.

His episcopal motto, taken from the Second Letter to Timothy, called on believers to pursue justice, faith, hope, love and peace together with those who call on the Lord with a pure heart, and his coat of arms took the form of a pentagon recalling Pentecost.