Imamura Execution Ground
The populace of the Shimabara domain converted en masse to Christianity in 1579, after daimyo Arima Harunobu (1567–1612) chose to be baptized. Following Harunobu’s death in 1612, however, his son Arima Naozumi (1586–1641) abandoned Christianity and began to persecute the local Christians, albeit not very zealously. The shogunate briefly took over the administration of the domain before awarding it to Matsukura Shigemasa (1574–1630) from Yamato Gojo Province (modern-day Nara) in recognition of his martial prowess in 1618. The move quadrupled his income, so Matsukura was eager to please the authorities. Once the local people had built him a magnificent new castle, he set about persecuting the resident Christian population, coming up with sadistic innovations such as boiling them alive in the hot springs of Unzen.
Many Christians were killed at this execution ground, including an Italian priest named Navarro and 56 Catholics from the Omura domain. In the mid-nineteenth century, the bodies of the executed were given to Ichikawa Taiboku and Kaku Saichiro, doctors whose anatomical diagrams contributed significantly to the advance of Japanese medicine. The execution ground remained in use until 1875.