According to "Gunkan," or "Takeda sandaiki" (a history of the three generations of the Takeda family), a wisp of cloud floated over ubuya (a hut for delivering babies) as if a white flag fluttered in the wind, and when it disappeared, a pair of white falcons came to stay over the ubuya (a hut for delivering babies) for three days.
『軍鑑』や『武田三代記』などによれば、信玄誕生のとき、産屋の上に一条の雲がたなびき白旗の風に翻るように見えたが、それが消えたとき一双の白鷹が3日間も産屋にとまったとされる。