Guin Saga - Kurimoto, Kaoru

In ancient times, the King of Paroh is savagely murdered with his wife and servants in his castle by mercenaries from the Gohra army. Only his children, Prince Remus and his twin sister Princess Linda, managed to escape during the massacre in the surrounding forest. Quickly caught up by bloodthirsty murderers, they are saved by a strange-warrior with the face of a leopard. Suffering from amnesia, the mysterious savior only remembers his name: Guin. Twins explain him their situation and decide to help Guin hoping to learn more about its origins. On their way, they meet some allies including a young girl from an ape-people, a mage and a mercenary by the name of Isht Van. The small group will rally the tribes Sem and legendary giants, the Lagons, to expel the invaders and to avenge the massacre committed by Gohra.

(Source: MangaTraders)

Guin Saga is based on the late Kaoru Kurimoto's novel series of the same title.