Jukeini was the formal wife of Imagawa Ujichika, the ninth lord of the Imagawa clan, and the military governor and sengoku daimyō of Suruga Province. Jukeini originated from the Naka-no-mikado family affiliated with the Fujiwara-hokke, one of four Fujiwara families of nobility. Her father was Naka-no-mikado Nobutane, the Provisional Chief Councilor of State. Her elder brother was Naka-no-mikado Nobuhide and elder sister the formal wife of Yamashina Tokitsuna. Children included Imagawa Ujiteru, Imagawa Yoshimoto, and Zuikei-in (the wife of Hōjō Ujiyasu). After the death of her husband, Ujichika, Jukeini shaved her head and became a nun at Zuikoin, a Buddhist temple in Kyōto, under the name of Ōkata-dono. She supported governance of the clan over four generations including Ujichika, Ujiteru, Yoshimoto, and Ujizane. Jukeini wed Ujichika in either 1505 or 1508. In 1513 she bore Ujiteru, followed by Sangorō and, in 1519, her third son, Yoshimoto.
While attending to her husband during a prolonged illness for over ten years, Jukeini and close associates may have drafted a set of provincial laws known as the Imagawa kana mokuroku for distribution under the name of Ujichika. The use of kana characters mixed with kanji characters is viewed as possible evidence of Jukeini’s role in drafting the provisions, but many provincial laws were written with a mix of kana and kanji characters, such as laws promulgated by the Sagara, the Jinkai, and the Yūki clans.
In 1526, after Ujichika became ill and Ujiteru succeeded him at the youthful age of fourteen, Jukeini issued official documents under her own seal for two years until Ujiteru became sixteen and managed provincial affairs on behalf of the Imagawa. Jukeini received this seal from Naka-no-mikado Nobutane when she married Ujichika. Consequently, she was referred to as Amamidai (尼御台). There are twenty-five letters issued by Juekini, with thirteen during the era of Ujiteru. Jukeini also helped arrange the marriage between Takeda Harunobu (a sengoku daimyō from Kai Province), and Sanjō-no-kata, his formal wife, who originated from the Sanjō family of nobles.
In 1536, following the successive deaths of Sangorō and Ujiteru, Jukeini became a nun. She had her son, Yoshimoto (who at the time had the name of Sengaku Shōhō), return to secular life. This led to a succession struggle known as the Hanakura Conflict waged between Yoshimoto and Genkō Etan (the son of a mistress of Ujichika) for control of the Imagawa clan. According to one theory, Jukeini may have given her support to Etan instead of Yoshimoto. Nevertheless, Yoshimoto defeated Etan and took control of the clan until he was killed in 1560 in a surprise attack by Oda Nobunaga at the Battle of Okehazama. Yoshimoto was succeeded by his grandson, Ujizane.
Jukeini died in the spring of 1568 in the midst of the collapse of the Imagawa clan. She is believed to have been in her seventies or eighties. Following her demise, the Imagawa and the Takeda severed relations and the Takeda invaded the Imagawa territory in an event known as the Invasion of Suruga. Ujizane fled to Tōtōmi Province and surrendered the following year to Tokugawa Ieyasu, whereupon the Imagawa clan as a sengoku daimyō perished.