According to its written guarantee of origin, a family treasure of the Takeda family "Tatenashi-no-yoroi" was the one given to Empress Jingu when she prayed at Sumiyoshi-taisha Shrine for long-lasting luck in the battle of Sankan seibatsu (the conquest of three countries in old Korea), and it later came into the possession of the Koshu Takeda family for a certain reason (needless to say, it is not a historical fact because the age of Sankan seibatsu doesn't coincide with the dates)
由緒書きによると、武田家の家宝「楯無」の鎧は神功皇后が三韓征伐の時に住吉大社に武運長久を祈念し得た鎧であり、ゆえあって甲州武田家の所有するところとなった（無論三韓征伐云々の伝記は時代的に合わないので史実ではない）。