Guin Saga

The story centres around a mysterious warrior named Guin, an amnesiac with a leopard mask magically affixed to his head. Remembering nothing but his fighting instincts and the word "Aurra", he confronts a world laden with danger, intrigue, and magic.
The manga is based on the early part of the story and is adapted to manga format by Hajime Sawada, as part of the Jive series Kurimoto Kaoru The Comic, adapting Kurimoto's works to manga form.
(Source: Wikipedia)