Saint Nikolai of Japan, Nikolai Kasatkin (born Ioan Dimitrovich Kasatkin August 1 of Julian calendar/ August 13 of Gregorian calendar, 1836 ; died February 16, 1912) was a Russian Orthodox priest, monk, and saint. He introduced the Eastern Orthodox Church to Japan. The orthodox cathedral of Tokyo (metropolitan diocese of Japan), Tokyo Resurrection Cathedral, has been nicknamed after him as Nikolai-do by the local community, as he lived in its bishop's house.

Nikolai was born on August 1st in Smolensk prefecture, 1836 (in the Russian calendar), son of Dimitry Kasatkin, a Russian Orthodox deacon. His mother died when he was five years old. He grew up in the church hierarchy: in 1857 he entered to the Theological Academy in Sankt Peterburg. In July 7 , 1860 (along the Julian calendar, Gregorian July 19) he became a monk and chose the name of Nikolai. Nikolai was appointed as a deacon in July 12 (July 24) in the same year, in the day of saints Peter and Paul and at the next day July 13 (July 25) was appointed as a priest, on the day of twelve Apostles, the commemoration day of the Chapel SS. Twelve Apostles belonging to the Academy.

On July 2, 1861 Nikolai landed at Hakodate, Hokkaido, Japan as a priest to the chapel of the Russian consulate in Hakodate. He was voluntarily appointed to this duty, attracted since the day he had noticed a poster calling for a priest for this chapel when he had been a seminary student; he had studied Japanese and quickly gained mastery of the Japanese language. While at consulate chapel, he converted three Japanese. Later, he moved to Tokyo, and made the city the see of the Bishop of Japan. His commission covered all of Japan: more than 250 churches were built under his mission. He was elected the first bishop of the Japanese Orthodox Church, and after the Russo-Japanese War was appointed archbishop.

During the war Nikolai stayed in Japan. Those days were very difficult for him -- his love for his birthland Russia conflicted with his obligation as the bishop of Japan to pray for the Japanese Emperor and the Imperial Army and Navy. Nikolai therefore held no mass during the war, instead encouraging Japanese faithfuls both to pray for and to contribute to the Army and Navy. Some encouraged him to go back to Russia but he refused and worked eagerly for Japanese faithfuls and Russian captives. In a letter on the conditions of a camp in Hamadera, Osaka, Nikolai wrote of his astonishment at the Russians soldiers' illiteracy: nine of ten captives couldn't read. Nikolai sent priests and teachers to camps who educated and cared for the captives. His attitude and manners impressed not only the Orthodox faithful but also non-Christians. Even Emperor Meiji was impressed with his character, especially his Christian and diplomatic efforts between the Russian Imperial Household and the Japanese government. When the Russian Tsar Nikolai II had been the crown prince of Alexander III, young Nikolai II had visited Japan and was injured by a mentally-ill Japanese policeman, Otsu Jiken , Bishop Nikolai made a great effort to resolve this incident.

Nikolai's study of Japanese was fruitful, allowing him to translate all liturgy books and many parts of the Bible including the whole of the New Testament, Psalms, Genesis, and the Book of Isaiah with help from a Japanese Christian and scholar Nakai Tsugumaro who ran a famous kanbun private school Kaitokudo in Osaka. Nikolai was the first saint of the Japanese Orthodox Church. After his death his body was buried in Tokyo Metropolitan Yanaka Cemetery , near Ueno. In 1970 he was canonized as Equal to the Apostles of Japan, Archbishop, St. Nikolai. His feast day is February 16. The Russian Orthodox Church and the Japanese Orthodox Church celebrate this feast nationwide.