Tokugawa Ieyasu's headquarters during the Battle of Nagashino according to the Shincho Ko-ki was Takamatsuyama. However, according to Owada Tetsuo/Kobayashi Yoshiharu's Nagashino-Shitaragahara no Tatakai, Ieyasu's camp has several listings.
Nagashino-Shitaragahara no Tatakai, p. 82.
Takamatsuyama Shincho-Ko ki and Shinchoki
Yatsurugi Takamatsuyama Matsudaira-ki
Danjouyama Nagashino nikki and Sokenki
Nothing noted down Mikawa Monogatari
Here is a link with photos of Tokugawa Ieyasu's camp at Yatsurugi Jinja
Nagashino-Shitaragahara no Tatakai is a must read for anyone who is studying the Battle of Nagashino. A must have no matter what. The book is difficult to read, but has tons of rich data.
Nobunaga no tame!