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