Munakata Saikaku (宗像 才鶴) was a Japanese female samurai warlord, aristocrat and onna-musha of the Sengoku period.

After her husband's death in 1586, she was appointed leader of the Munataka clan by Japan's most powerful man at the time, Toyotomi Hideyoshi.

The letter was discovered on September 18, 2019, attracting the attention of several people because of a peculiar fact in Japanese history: A woman being appointed as head of a clan by a powerful feudal lord.

[citation needed] In the "shuinjo", the warlord instructs the Munakata clan to consult with his vassal, Asano Nagamasa, before sending troops to Kyoto.

Although Saikaku is mentioned as the female lord of the Munakata clan in letters passed down to other samurai families, little had been known about her life and fate.