Kazumasu negotiate and convinced his cousin, Tanetoshi, to switch sides joining Hideyoshi and giving up the castle to him. Later, Kazumasu and Tanetoshi then attempted to attack Oda's, nearby Ono castle, but they were repulsed by Oda Nagamasu, when the Oda defenders threw torches into the attackers' boats.
Kazumasu mediated a deal with his cousin, Tanetoshi, convincing him to defect to Hideyoshi's side and surrender the castle. Kazumasu and Tanetoshi then launched a failed assault on Oda's Ono castle, which was repelled by Oda Nagamasu after the defenders set fire to their boats.