A church built while Christianity was still banned
Even though Japan had been opened, Christianity still hadn't been officially recognised. The construction of Oura took place in the midst of this.
In 1644, the last priest residing in Japan, Father Konishi Mansho, was martyred. From that time on, Christianity in Japan was so severely prohibited that on the eve of the opening of Japan in the mid-nineteenth century, it was thought unlikely by Europeans that there were any Christians left in Japan. The pope at the time, who was keen for missionary work in Japan to finally be resumed after so long, entrusted the Paris Foreign Missionary Society with the task of reevangelising Japan. They entered the Ryūkyū Kingdom (modern Okinawa) and waited for their chance.
Once Catholic missionaries had been legally permitted to enter Japan, they began to erect churches in Japan’s foreign settlements. In 1862, the first church was built in Yokohama. At that time, there was an incident where some Japanese who had gone to the church to have a quick look were arrested. This was because the ban on Christianity in Japan was still in force, and no Japanese person was allowed to be a Christian.