In 1637 an uprising comprised of mainly Japanese peasant Catholics was brutally crushed by the Tokugawa Shogunate, with almost 37,000 rebels and supporters beheaded and buried in the ruins of their castle stronghold.
The shogunate, accusing Portugeuse settlers, implemented the Sakoku (鎖国 – Locked country) policy, limiting foreign influence and forbidding Japanese citizens from leaving. Catholic missionaries and priest were expelled and converts either killed or tortured.
This started the sect of the Kakure Kirishitan (隠れキリシタン – hidden Christian). Worshiping in secret rooms they adapted prayers learnt from memory to sound like Buddhist chants and idols of the Virgin Mary and crucifixes were built in Buddhist styles. Eucharist was performed with rice and Sake.
Over time the original meanings of the prayers were lost and the Kakure Kirishitans beliefs became more ancestor worship based, with Christian martyrs taking the place of actual blood relations.
When religious sanctions were lifted in the mid 19th century many of the Kakure returned to the Catholic church. Only a handful remained.
In 1991, anthropologist Christal Whelan traveled the Goto Islands, southern Japan to speak with the few surviving Kakure Kirishitans. A preview of her documentary Otaiya; Japan’s Hidden Christians can be seen on Youtube.