The game is based on the manga series Moryou Senki Madara. The story is set in a mythological era in Japan, and focuses on twin brothers, Madara and Kage-Ou ("Shadow King"), sons of the evil Emperor Miroku. While Kage-Ou follows in the footsteps of his father, Madara fights against him and for the good of mankind. The game begins as Madara is gravely wounded in his fight against Miroku, but is saved by a young warrior named Seishinja, who lives together with his sister Himika. Before Madara is cured, Seishinja has to fight demons himself, with the help of the legendary sword Kusanagi.

[from MobyGames]