I have just read a very interesting article about Christianity in Japan:
http://en.wikipedia.org/wiki/Kirishitan
The Japanese at first took Catholicism for some sort of new sect of Buddhism. This made the task of missionaries easier.
However, "the uncompromising Xavier took to the streets denouncing, among other things, infanticide, idolatry and homosexuality (the last being widely accepted at the time). Misunderstandings were inevitable."
-"By the end of the sixteenth century, the Japanese mission had become trhe largest overseas Christian community that was not under the rule of a European power".
-"Accepted on a national scale, Christianity was also successful among different social groups from the poor to the rich, peasants, traders, sailors, warriors, or courtesans. Most of the daily activities of the Church were done by Japanese from the beginning, giving the Japanese Church a native face, and this was one of the reasons for its success."
By 1590, one half of Jesuits in Japan were Japanese.
-"Nagasaki was called the Rome of Japan and most of its inhabitants were Christians. By 1611 it had ten churches."
-"By 1587, Hideyoshi had become alarmed. Not because of too many converts, but rather because Christian lords repeatedly ovdersaw forced conversions of retainers and commoners, that they had garrisoned the city of Nagasaki, that they participated in the slave trade of other Japanese and, apparently offending Hideyoshi's Buddhist sentiments, that they allowed the slaughter of horses and oxen for food."
-"Between 1557 and 1620, eighty-six Daimyos were baptized, and many more were sympatrhetic to the Christians."
-"From the correpondence between the Portuguese King Joao III and the Vatican Pope of the period, it is written that the Christian Daimyos sold women into slavery for the Jesuits' gunpowder at a going rate of 50 baptized Japanese girls for a barrel of saltpeter. As many as 500,000 Japanese girls were sold on the slave markets and shipped to South America and Europe."
-"In 1567, Hideyoshi Toyotomi called the marrano Gaspar Coelho to command to stop slave trade of Japanese women and bring back all the Japanese."
Tokugawa Ieyasu was not as lenient as his predecessor. He demanded the expulsion of all European missionaries and the execution of all converts. The systematic persecution began in 1614.
-"The Shogunate was concerned about a possible invasion by colonial powers, which had previously occurred in the New World and the Philippines."