Yotaiin (1541 - February 1, 1629) was a legal wife of Naoshige NABESHIA, the founder of the Saga domain in Hizen Province. She was the second daughter of Tsunenobu ISHII, the lord of Iimori-mura, Yoka no sho, Saga-gun, Hizen Province (present Kanoko, Honjo-machi, Saga City, Saga Prefecture). Her mother was Rengein (also known as Nicchoni), a daughter of the Kuro clan, which was a branch family of the Kyushu Chiba clan. Her name was Hikotsuruhime, but she was also called Fuji no kata. It is said that she was a brave, clever, and merciful woman. In her home Saga Prefecture, she is revered as a wise wife as well as the mother of the nation; even today, she remains a popular historical figure along with her husband Naoshige. To put it in modern-day language, she married Naoshige for love, which was rare at the time. Like the couple of Toshiie MAEDA and Hoshunin and the couple of Kazutoyo YAMANOUCHI and Kenshoin, the couple of Naoshige and Rengein was one of the most well-known couples in the Azuchi-Momoyama period.
She was born in Iimori-mura, Yoka no sho, Saga-gun, Hizen Province as the second daughter of the couple of Tsunenobu ISHII (a senior vassal of Takanobu RYUZOJI) and a daughter of the Kuro clan. Her eldest brother was the brave general Tsunetada ISHII, who was a bodyguard of Takanobu, her eldest sister was Hoshoin, who was the wife of Tadatoshi ISHII, her younger brother was Katatsugu ISHII, who was the chief retainer of Masaie RYUZOJI, and her younger sister was Nikkini, who was the wife of a vassal of the Nabeshima clan Nobufusa SUGIMACHI.
Though Yotaiin married Nobusumi NOTOMI, a chief retainer of the Ryuzoji clan, she returned to her parents' home with her daughter because Nobusumi had died in battle soon after the marriage. When she was at her parents' home, Takanobu RYUZOJI and Naoshige NABESHIMA called at the residence of Tsunenobu ISHII on the way back from a battlefield and had lunch. People of the ISHII clan was embarrassed with the unexpected visit of the lord, started to broil sardines hastily for lunch. However, it took time to broil all the sardines needed to serve a lot of people.
Yotaiin, who was watching the scene, went to the kitchen and pushed aside the handmaids, saying, 'You're too clumsy.'
She then picked up the burning firewood from the stove, scattered it on the garden and threw numerous sardines into it. She then put the broiled sardines in a bamboo basket, shook off the ashes and quickly served them to Takanobu and others.
According to "Hagakure" (the record of the Nabeshima domain), Naoshige, who was watching everything, was consumed with the desire 'to marry such a quick-witted woman.'
Thereafter, he began visiting the Ishii family frequently, asked her to marry him, and finally she did.
Thus, she became the legal wife of Naoshige NABESHIMA and supported her husband, who was active as the strategist of the Ryuzoji clan behind the scenes. She had four children with Naoshige: the eldest daughter Chizuru (the wife of Yasutoshi TAKU, a chief retainer of the Saga domain), the second daughter Hikogiku (the wife of Naotaka ISAHAYA, a chief retainer of the Saga domain), the eldest son Katsushige NABESHIMA (the first lord of the Saga domain) and the second son Tadashige NABESHIMA (the first lord of the Kashima domain).
According to "Hagakure," she was happy with Naoshige throughout her life, and after Naoshige retired, she spent her last days in peace and quiet together with him. There is also a description that she, as well as her husband, showed consideration for vassals and the people of the domain.
Yotaiin died at 89 years of age, satisfied herself that the Nabeshima clan become the lord of the Saga domain both in name and reality. That was ten years after her husband Nobushige died and she entered the priesthood. Her grave was constructed next to that of Naoshige at Koden-ji Temple, the ancestral temple of the Nabeshima clan. Her gravestone was the stone that Naoshige had used as a pillow for one night during the battle in Korea and brought back to Japan.