Myōin-ni was a woman who lived during the Sengoku period. She was born in 1514. Myōin-ni became the wife of Yura Narishige, the lord of Nitta-Kanayama Castle in Kōzuke Province.
There are also theories that Myōin-ni was the daughter of Akai Shigehide or Akai Iekata. She wed Yura Narishige and bore Yura Kunishige and Nagao Akinaga. After the demise of Narishige in 1577, she entered the priesthood.
In 1583, after the Hōjō clan came into conflict with the Yura clan, she attempted to ally with Toyotomi Hideyoshi and Tokugawa Ieyasu. Later, although Nitta-Kanayama Castle was requisitioned by the Hōjō clan, she continued to serve the Yura clan.
In 1590, after Toyotomi Hideyoshi launched the Conquest of Odawara, she defended Kiryū Castle (also known as Hishakuyama Castle) while her son, Yura Kunishige, was holed-up in Odawara Castle. On 6/7 of the same year, she surrendered via Maeda Toshiie to the Toyotomi army. Thereafter, Myōin-ni cooperated with the Toyotomi by having her grandson, Yura Sadashige, lead a contingent of 200 soldiers in support of an assault on Matsuida Castle. In the eighth month, Myōin-ni received landholdings for Ushiku Castle in Hitachi Province as a forbearance reward while Kunishige was permitted to retain his family name.
She died on 11/6 of Bunroku 3 (1594) in Ushiku.