The story follows Demon Eyes Kyo as he seeks to regain his body after his soul was sealed inside the body of his rival, Mibu Kyoshiro (or "Kyoshiro Mibu" when written in western order). Kyo is joined in his search by, among others, the bounty-hunter Shiina Yuya, Benitora (who is actually Tokugawa Hidetada, heir to the shogunate), and Sanada Yukimura, a famous rival of the Tokugawa.
-taken from wikipedia

Picture	Real Name	Description
	Demon Eyes Kyo	He is known for his glowing, blood-red eyes, is one of the greatest and most feared samurai in the world. He carries a legendary nodachi called Tenro (Heavenly Wolf), made by mastersmith Muramasa. When he was young, he was shunned by all of the Mibu clan except for the Sendai Aka no Ou (Former Crimson King). After killing Oda Nobunaga, he was thrown into the Mibu dungeons until Muramasa rescued him and trained him in the Mumyo Jinpu Ryuu. Kyo is the last remaining real Mibu.
	Mibu Kyoshiro	A remarkable swordsman, depicted as the only rival to Demon Eyes Kyo. He wielded (before Sasuke did) the Shibien (Purple Sword), a Muramasa. In the manga, he is depicted as one of the heirs to the Aka no Ou throne, the Red Eyes were proof of his Mibu lineage. He is a "Red Cross Knight", created from the flesh of the former Aka no Ou. Though he is able to control the Shin Red Eyes, he is not a true Mibu, but merely a more advanced type of battle doll.
	Shiina Yuya	A girl who makes a living as a professional bounty hunter in order to track down the "Man with the Scar on his back" who killed her brother, Nozomu. She uses a three barreled gun and small daggers, strapped to her thigh. Shiina Yuya was actually an orphan found by Nozomu and raised by him.