According to Masahiro TAKAHASHI, a researcher of medieval Japanese history living in Tottori City, Takeda Buzen no kami was at Tottori-jo Castle when he was involved in the murder of Nobumichi YAMANA plotted by Suketoyo YAMANA of Tajima Province ("Sanin Sengokushi no Shomondai: jo" [Issues in the Sengoku History of Sanin region: first volume], written by Masahiro TAKAHASHI in 1993).
鳥取市在住の中世史研究家・高橋正弘によると、武田豊前守は鳥取城にあって但馬国の山名祐豊に呼応して山名誠通の殺害に一役買ったとされる（高橋正弘『山陰戦国史の諸問題・上』1993年）。