Especially when Masashige KUSHIMA, the busho (Japanese military commander) of the Imagawa clan, led a force of 15,000 samurai and invaded in Kai Province in 1522, Nobutora achieved a triumph over the troops by making a surprise attack at the headquarters of army and decapitated Masashige with an army of only less than 2,000 samurai (Fukushima intrusion incident).
特に、大永2年に今川氏の武将福島正成が1万5千を率いて甲斐に侵攻してきたとき、信虎の兵力は2千に満たなかったが、本陣に奇襲を仕掛けて打ち破り正成の首をあげる大勝利を挙げている（福島乱入事件）。