In the "Koyo Gunkan" (record of the military exploits of the Takeda family), which was not clearly authenticated (Quite a few parts were modified by the Tokugawa Shogunate, given that it was not written by Shinegn himself and was completed in the early Edo period) the following was written:
このことに関して信憑性は今ひとつである『甲陽軍鑑』（元々信玄本人が著したのではないのと、成立が江戸初期という事で、徳川幕府の手が加わっている個所が多々見られる）の記述がある。