Harunobu Arima is well known as a Christian daimyo, however, in the beginning, he distanced himself from Christianity and even destroyed churches built during the age of his father, Yoshisada. However, Harunobu was later baptized as a necessity to protect his territory, but gradually, he developed a sincere faith in Christianity.
Being widely informed through foreign trade, Harunobu was one of the few people in Japan who held an international perspective, and therefore was highly respected by the Society of Jesus and the missionaries. We will take a look at the early years of the Christian daimyo, Harunobu Arima.
In 1571, at the age of only four, Harunobu became the head of his family following the death of his older brother, Yoshizumi. Now Harunobu is well-known as having been a devoted Christian, however it did not mean that he was so from the beginning. When his father, Yoshisada, was ill in bed and wished to see a missionary, Harunobu refused his request. Even after the death of his father, he destroyed churches and crosses. At first, Harunobu distanced himself from Christianity.
Nonetheless, things changed when Takanobu Ryuzoji of Saga started to gain enough power to terrify Arima. Harunobu now needed to seek help from the missionaries and the Society of Jesus. Father Valignano arrived in Kuchinotsu in 1579. The following year, Harunobu decided for himself to become a Christian and was baptized. He was only thirteen years old. In order for this young boy to obtain enough military and economic strength to rival the Ryuzoji Clan, he needed the Jesuits' help.
In addition, Harunobu also sought help from the Shimazu Clan who were also against the Ryuzoji Clan. He received support from both the Society of Jesus and the Shimazu Clan to fight against the Ryuzoji Clan. In March, 1584, leading tens of thousands of troops, Takanobu Ryuzoji invaded the northern part of the Shimabara Peninsula. The combined forces of Arima and Shimazu met their enemy with only 6,000 to 8,000 soldiers. The armies faced each other in Okitanawate (near present-day Kitamonmachi, Shimabara City) and the battle began. It is believed that the canons donated to Harunobu by the Society of Jesus were a major contribution to the power they demonstrated. Despite the fact that they had an overwhelming disadvantage with the incomparable size of their military, the combined forces of Arima and Shimazu were able to defeat Takanobu.
As a reward for the victory, Harunobu donated Urakami Village in Nagasaki, which was part of the territory he ruled at the time, to the Society of Jesus. Christianity had already been propagated in Urakami, but the donation triggered deeper rooting of Christianity in the area.
Free from the threat of the Ryuzoji Clan, Harunobu was now unleashed. However, he found himself in the middle of a conflict between the Shimazu Clan and the Society of Jesus, who both supported him in the war. Initially, the Society of Jesus hoped to receive Unzen, not Urakami Village, as a reward from Harunobu, but the Shimazu Clan was completely against it. Satsuma (Kagoshima) and the Shimazu Clan were devout believers in Buddhism, and they hoped that the temples, monasteries and Buddhist statues be rebuilt in Unzen, which was also a holy mountain for mountain ascetics. Additionally, Unzen produced sulfur, which was used to make gunpowder, and therefore they might have thought it perilous to hand over such a place to foreigners. Whenever the Shimazu Clan had an opportunity, they urged Harunobu to eliminate Christianity.
It was during this time that daimyo Yukinaga Konishi (who was later to become the feudal lord of Higo Uto Castle) was inviting priests to his territory of Shodoshima to encourage propagation of Christianity, and at the same time, he played an important role in connecting daimyos in Japan with Hideyoshi Toyotomi. At the time of Hideyoshi’s Kyushu Campaign, Harunobu forwent an alliance with the Shimazu Clan and through Yukinaga, joined Hideyoshi’s side, resulting in the capitulation of the Shimazu Clan and the subjugation of Kyushu. In the subsequent division of territories in Kyushu, Harunobu was appointed Daimyo of the Shimabara peninsula, while Yukinaga governed Higo (Kumamoto) in Uto Castle. Most of the population in Amakusa at this time were said to be Christian. Collegio and noviciado (novitiates), where the four boys of the Tensho Mission would study, were also built later on. Yukinaga protected and supported these Jesuit activities in Amakusa.
It can truly be said that Christianity supported Harunobu throughout the difficulties of the Kyushu Campaign, as well as the war against the Ryuzoji Clan. He was able to survive in the maelstrom of war by believing in Christianity. At first, he may have been baptized just as a means of protecting his territory, but later in his life, he came to have truly unshakable faith in Christianity. After the Kyushu Campaign in July, 1587, Hideyoshi promulgated the Bateren-tsuiho-rei (the order expelling Jesuit missionaries). However, Harunobu provided sanctuaries within his territory for missionaries and seminaries.
On August 13th, 1590, the Jesuit General Council was held and missionaries from all over Japan came to Kazusa in Arima’s territory. They decided to print Christian booklets using the Gutenberg printing press that the Tensho Mission had brought back, as a method to continue propagation of Christianity under the ban. The first Japanese booklet using metallic type, “Sanctos no Gosagveono (Works of the Saints)” was printed in Kazusa. These Jesuit activities were possible in Harunobu's territory solely because of his guardianship of Christianity and his ability to guarantee the safety of missionaries.