He received his episcopal consecration on 16 September from Seiichi Shirayanagi, with Archbishops Paul Hisao Yasuda and Francis Xavier Kaname Shimamoto serving as co-consecrators.

Following the early resignation of Cardinal Shirayanagi, Pope John Paul II appointed him Archbishop of Tokyo on June 12, 2000.

On October 27, 2012, Pope Benedict XVI named Okada a member of the Pontifical Council for Interreligious Dialogue.

[2] In January 2011, the Holy See countermanded the decision of Japan's bishops to suspend the activities of a controversial lay movement, the Neocatechumenal Way, for five years.

[4] Pope Francis accepted his resignation on October 25, 2017, and appointed Bishop Tarcisio Isao Kikuchi, S.V.D.