Yoshinobu was Shingen's eldest son. His mother was the daughter of court noble Sanjô Kimiyori. Yoshinobu was granted the use of the character 'Yoshi' (義) from shôgun Ashikaga Yoshiteru and in 1552 married a daughter of Imagawa Yoshimoto. He argued with his father over the conduct of the Fourth Battle of Kawanakajima (1561), where he was wounded, as well as disagreed on what to do about the Imagawa clan in Suruga province after the death of his father in law, Imagawa Yoshimoto. He went so far as to lobby his position to Shingen's generals behind his back, and relations between father and son soured after this. In 1565 he was accused of plotting against Shingen and was confined to the Toko temple. Meanwhile, Obu Toramasa, his tutor, was ordered to commit suicide. The information of the alleged plot against Shingen was brought to light by Yamagata Masakage.
In 1567 Yoshinobu was made to commit suicide. Another theory has it that he died of illness, though many historians accept that Shingen ordered his death, possibly to insure that Takeda Katsuyori would succeed him.
- Initial text from Samurai-Archives.com FWSeal & CEWest, 2005