Shingen's heir Takeda Katsuyori was decisively defeated in the battle of Nagashino (1575), losing more than 10,000 men and the core of his generals.

In response, on 14 February Nobunaga's army under his son Oda Nobutada invaded Shinano province from the west, rapidly advancing east as Takeda garrisons defected or surrendered without a fight.

At the same time Tokugawa Ieyasu invaded the province of Suruga, which capitulated on 25 February 1582. by defection of some chief retainers and relatives of Takeda Katsuyori.

Oda Nobutada occupied the old Kai capital of Kōfu on 7 March 1582. and had all of Takeda Katsuyori's family, relations and house elders hunted down and executed.

They put up a temporary palisade around an ordinary manor house in a village called Tano (east of Kōfu) and made their last camp there.

On 11 March, Oda general Takikawa Sakon picked up information that Takeda Katsuyori and his kin had retreated into the mountains of Kogakko.