Ōtomo Sōrin (大友 宗麟, January 31, 1530-June 11, 1587) was a Sengoku era daimyo, head of one of the most powerful clans on the island of Kyūshū, among those who, upon meeting St. Francis Xavier, converted to Christianity.
Initially known as "Ōtomo Yoshishige," the eldest son of Ōtomo Yoshiyaki, he took over the clan when his father was murdered when he was ready to disinherit him
. He then continued the territorial expansion begun by his father, confronting and defeating the Kikuchi clan in 1551, then subduing the Akizuki clan in 1557. A few years later, in 1561, began a struggle of several years with the Mori clan, interrupted in 1562 and resumed in 1568.
At the end of this war, the Mori clan extended its influence at the expense of other clans on the island, such as the Ryūzōji clan.
Later still, after their conversion to Christianity, Yoshiaki, who became Sōrin after a first religious conversion as a Buddhist monk and kept that name once he became a Christian, and his son Yoshiatsu, attempted to take advantage of the defeat of the Itō clan at the hands of the Shimazu to occupy the north of Hyuga province, against the advance of the latter, and to establish a Christian city there.
Unable to obtain Toyotomi Hideyoshi's help against their new enemy, they launched an operation that would lead, in 1578, to the battle of the Mimi-gawa and the first disaster for the Ōtomo. Their power then declined in favor of the defeated former enemies Akizuki and Ryûzôji.
In 1586, however, it was the Ryūzōji clan that suffered a major setback through the death of chief Takanobu in a battle against the Shimazu. Sōrin then tries once again to appeal to Hideyoshi, going to meet him in Osaka. This time the latter reacted favorably.
After another defeat of the Ōtomo at the battle of the Hetsugi-gawa, Hideyoshi's troops arrived in Kyūshū and won against their opponents to unify the island under their rule. Sōrin died that same year with the confidence that he had been able to install his clan's power over his domain, despite the loss of autonomy.
A few years later, his son Yoshimune, as a result of a few more mistakes, would lead the clan to its demise.
Ōtomo Yoshishige met the Jesuit missionary Francis Xavier in 1551 and quickly embraced European culture. He quickly adopted both its customs and military technologies to the point that it is ultimately unclear whether his future conversion to Christianity was an act of faith or a political and economic strategy.
In 1562, Portuguese aid was actualized to the point that Sōrin benefited from three ships of that nationality during the siege of Moji Castle, which would ultimately prove to be a defeat for him.
In any case, for about fifteen years, Western influence still blended with Japanese culture and did not prevent him from becoming a Buddhist monk in 1562 under the name "Sōrin."
In 1578, he eventually adopted the Christian religion and was officially baptized, three years after allowing his son Ōtomo Chikaie to do so. This conversion would be accompanied by a zeal that went so far as to burn Buddhist and Shinto temples despite the protests of the priests, promising vengeance from the gods.
It was in this same year that the expansion of the Ōtomo's power would cease in favor of the Shimazu. It should be noted, however, that this apparent fanatical fury may have political motives, as certain temples or sects may have great influence and power both culturally and politically or militarily.
But the links do not stop at profits on Japanese territory. Thus, in 1582, Ōtomo Sōrin sent, along with the two other Christian daimyos of Kyūshū, Ōmura Sumitada and Arima Harunobu, the first Japanese diplomatic mission to Europe, to Rome, to the pope: the Tenshō embassy.