How many Christians are there in Japan?

According to the Yearbook of Religions compiled by the Agency for Cultural Affairs, the total number of Christians of various sects in Japan was approximately 1.91 million in 2002.
Christianity was first introduced to Japan in 1549, and was propagated mainly by Spanish and Portuguese Catholic missionaries of the Society of Jesus including Francisco Xavier.
In a short period of time Christianity acquired many believers, and their numbers reached 120,000 in 1580.
After 1640, when Christianity was banned, persecuted Christians had no choice but to live as kakure kirishitan (hidden Christians) until the Ｍeiji Restoration lifted the ban in 1868.
After World War II, when democracy and related ways of thinking were first introduced, the number of Christians increased rapidly, but the speed of growth has slowed down in the past couple of decades.