Donbori Matsuo was a friend of Miyamoto Usagi and a comrade of his throughout the three years before the death of Lord Mifune. Matsuo saved Usagi's life at the Battle of the Burning Plains, one of the lesser skirmishes before the Battle of Adachigahara. Matsuo was believed to have died at Adachi Plains; however, he survived, although he sustained dreadful injuries in the process. Matsuo followed his son, Donbori Chiaki, at a distance, and watched as his son became a fine samurai in his honour. Five years after his disfigurement, Matsuo met Miyamoto Usagi again, but he exacted a promise from Usagi that he would not tell Chiaki that Matsuo was still alive.