Kamakura Katsuo is daimyo of the Edo province in Japan, and later the Shogun (military ruler of all of Japan) after his victory in the Battle of Osaka Castle.
He is often disliked due to the fact he insists on the utmost respect, something which involves killing any person who does not bow when he rides past along various roads. Jack Fletcher finds this out in The Way of the Warrior, when a deaf tea merchant is killed by one of Kamakura's Samurai due to the fact he was unaware of his passing.
He would be the one that instigated the Battle of Osaka Castle, hiring ninja like Dragon Eye to his cause. Through devious tactics, he manages to win the war, and declares himself Shogun, claiming a Minamoto bloodline. One of his first acts as Shogun is to hunt down any foreigners and Christians - his prime target being Jack Fletcher, the only gaijin (barbarian) samurai.
He passes away in 1615, likely due to natural causes (however, this is never explicitly stated), and Takatomi takes his place as Regent of Japan until his heir can take up the reins of Shogun.