The siege of Kaminojo the Siege of Kaminojo was a battle during the Sengoku period (16th century) of Japan. With the help of his ninja vassal Hattori Hanzo, Tokugawa Ieyasu, after a well fought battle, ended up capturing the castle of Kaminojo from its keeper, Udono Nagamochi, a general of the Imagawa. Throughout Ieyasu's victory over the capturing of Kaminojo, Ieyasu obtained many useful hostages to use against that of the Imagawa, who were currently in possession of his own family.