Myōkōni was a woman who lived during the Sengoku period. Her common name was Ei. 

She was the daughter of Hayashi Michiyasu, a retainer of the Oda clan of Owari Province, and the wife of Mori Yoshinari (Yoshinari’s common name was Sanzaemon-no-jō).  With Yoshinari, Myōkōni bore six boys and two girls.  Her eldest son, Mori Yoshitaka, died during his first experience in battle at Tenzutsuyama Castle in Echizen Province.  Three of her other sons, Mori Naritoshi, Mori Nagataka, and Mori Nagauji, died during the coup d’état against their lord, Oda Nobunaga, known as the Honnō Temple Incident on 6/2 of Tenshō 10 (1582).

Hayashi Tameda was her older brother.

In 1596, she died at Kanayama Castle in Mino Province.