Chikamasu was the youngest son of Chosokabe Kunichika and a brother of Chosokabe Motochika. He suffered from tuberculosis and in 1571 set out to a hot spring in Awa province in an attempt to bolster his health. En route he was murdered by Awa samurai who mistook him for a spy. This is said to have provided Chosokabe Motochika with a pretext for his invasion of Awa province. Chikamasu was remembered as a big and cheerful individual, despite his flagging health.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005