Christianity's long history in the margins | The Japan Times Online:
Prime Minister Taro Aso may be a proclaimed Christian, but as far as the spread of the faith among the populace, it finds only a marginal presence.
Certain trappings of Christianity, however, have manifested themselves in modern Japan, particularly in terms of Christian-style weddings and the celebration of Christmas.
Though the article does not mention it, Orthodox Christianity arrived in Japan in 1861, with Fr Nikolai Kasatkin, who became the first bishop of Japan. Hewas originally a chaplain to the Russian consulate at Hakodate, and at the time of his death in 1916 the Orthodox Church numbered about 30000, but it seems to have stopped growing after his death.