Hatsume no Tsubone (初芽局) is a fictitious Japanese woman from the Sengoku period.[1] She is famous as the main character of the historical novel Sekigahara by Ryōtarō Shiba. In the novel, she is a kunoichi (female ninja) sent by Tokugawa Ieyasu to spy on his political enemy Ishida Mitsunari before the Battle of Sekigahara.[2]