According to local oral tradition, Toyonobu TAKEDA, the last head of the Kazusa-Takeda clan, was identified with Shingen's third son Nobuyuki SAIHO, and some people asserted that he sheltered his younger brother Morinobu NISHINA after the Kai-Takeda clan extinguished.
上総武田家最後の当主・武田豊信は地元の伝承では信玄の三男・西保信之と同一人物とされ、甲斐武田氏滅亡後に弟の仁科盛信の家族を匿ったという説がある。