was a retainer under the Tokugawa clan during the late Sengoku period of Japanese history. He was the eldest son of Hattori Hanzō. The eldest son of Hattori Hanzō, Masanari began to fight alongside his father by the mid 1590s, and succeeded him in 1596, when he was 31 years old. Following the Battle of Sekigahara of 1600, Masanari was enlisted by Tokugawa Ieyasu as captain of the Edo Castle guards, but ended up suffering from a scandal while in the process, more than likely justified by his harsh treatment to the band of Iga beneath his jurisdiction, it may also be because he wasn't a shinobi like his father [citation needed] causing him to be utterly humiliated in the face of the Tokugawa and relatively stripped from his initial position as captain. In order to repair the Hattori name and