Myōrin-ni lived during the Sengoku period. She was the wife of Yoshioka Akioki (later Shigeoki), a retainer of the Ōtomo clan. She is also referred to as Yoshioka Myōrin or Yoshioka Rinko. She appears as Myōrin-ni in the authenticated diaries of Luís Fróis, a Portuguese missionary residing in Japan during this period.
Myōrin-ni’s real name, origins, and date of birth are uncertain, but her father was Hayashi Sakyō-no-suke. Under one theory, it was Niu Kojirō Masatoshi. She wed the son of Yoshioka Nagamasu, Akioki, but, in 1578, he died at the Battle of Mimikawa so, to mourn for her husband, she entered the priesthood and thereafter was called Myōrin-ni.
Defense of Tsurusaki Castle
In 1586, in pursuit of a hegemony in Kyūshū, Shimazu Yoshihisa commenced an invasion of Bungo Province which was under the control of the Ōtomo clan. In the twelfth month, at the Battle of Hetsugigawa, the Shimazu defeated the Ōtomo despite support of the Ōtomo by reinforcements sent by Toyotomi Hideyoshi. This owed to blunders committed by Sengoku Hidehisa as the commander of Toyotomi forces. Notwithstanding the merits of the victory at Hetsugigawa, the Shimazu forces proceeded to vigorously subdue areas across Bungo. Riding the momentum, Shimazu Iehisa marched toward Usuki Castle (Niujima Castle), the base of Ōtomo Sōrin, and assigned a contingent of 3,000 soldiers to Nomura Fumitsuna, Shirahama Shigemasa, and Ijūin Hisanobu, ordering an attack against Tsurusaki Castle.
At the time, Yoshioka Munemasu, the surviving son of Yoshioka Shigeoki, was the lord of Tsurusaki Castle. Munemasu, however, had followed Sōrin by holing-up in Usuki Castle, so the command of Tsurusaki had been entrusted to his mother, Myōrin-ni (the widow of Shigeoki). Munemasu had taken the young soldiers with him so those remaining in the castle and its environs were limited to elder retainers, peasants, and women and children. Given their lack of military power, surrendering would have been a reasonable choice. Myōrin-ni, however, was not inclined to vacate the castle, and decided to resist. She had the peasants quickly bring boards and tatami mats as materials to build defenses around the castle, taught the peasants how to shoot arquebuses, and prepared for their defense in a showdown against the Shimazu army.
In the ensuing winter, after establishing a position on Mount Shirotaki, the Shimazu army led by Nomura Fumitsuna finally commenced attacks against Tsurusaki Castle. The attacking forces, however, encountered pits, traps, and tripwires, along with the skillful use of arquebuses as meticulously planned by Myōrin-ni, causing them significant harm. In the end, the members of the Yoshioka army led by Myōrin-ni repelled sixteen attempted assaults by the Shimazu forces, enabling them to hold the castle. Unable to make progress, the Shimazu army could not draw upon the main division which had other demands, so finally proposed a settlement. Faced with dwindling provisions in the castle, Myōrin-ni agreed to vacate Tsurusaki and withdraw on the condition that the lives of all of the defenders would be guaranteed. Upon reaching a settlement, the defenders led by Myōrin-ni were treated cordially by the Shimazu troops, with both sides exchanging drinks of saké inside the castle before departing.
The Battle of Terajihama
Although Myōrin-ni entered into a settlement, she did not give-up her desire to eviscerate the Shimazu army. In the third month of 1587, it was heard that Toyotomi Hideyoshi himself was leading an army of 200,000 men to come and subdue the Shimazu. After the Shimazu army posted in Bungo was ordered to retreat, Myōrin-ni visited the residence of Nomura Fumitsuna to explain that she had become close to the Shimazu army and could no longer remain with the Ōtomo family so she wanted his retainers to accompany her to Satsuma Province. Under the pretext of a celebration, she gave saké to the Shimazu troops. On 3/8 of Tenshō 15 (1587), as the Shimazu army departed, Myōrin-ni sent them off and said she would soon converge with their forces. Waiting for this moment, she stayed behind with her company while ordering her retainers to pursue the Shimazu forces during their slow retreat. In the environs of Otozugawa, the retainers launched a surprise attack that resulted in the killing of Shirahama Shigemasa, Ijūin Hisanobu, and many others. Nomura Fumitsuna was struck in the chest by a stray arrow. Although he somehow managed to escape to Taka Castle in southern Hyūga Province, he later died of his injuries.
On the day after the Battle of Terajihama (also known as the Battle of Otozugawa), Myōrin-ni sent 63 heads of the Shimazu clan to Ōtomo Sōrin at Usuki Castle. After hearing of her valor, Hideyoshi was impressed and said that he definitely wanted to meet her. However, Myōrin-ni was said to have refused. Her whereabouts thereafter are unknown, but her intelligence and bravery continued to be talked about by locals.
In 1593, after their lord, Ōtomo Yoshimune, was removed from his position, members of the Yoshioka clan also became rōnin, or wandering samurai, while Myōrin-ni’s base at Tsurusaki Castle was abandoned.