According to "Koyo Gunkan" (a record of the military exploits of the Takeda family), Matsusuke ATOBE and Mitsutaka NAGASAKA who were preferentially treated by Katsuyori (i.e., "Kunshin no Kan" or dishonest subjects toward their master) advised him to go to war so the battle was decided.
『甲陽軍鑑』などでは勝頼が重用した（いわゆる「君臣の奸」の）跡部勝資、長坂光堅らが決戦を進言して決定したとされる。