 Ayane, a young female ninja and one of the "DOA" regular cast members, acts as a guide throughout "Ninja Gaiden" by supplying advice and objectives to the player.Muramasa, a bladesmith, has shops scattered throughout the game world where players can purchase useful items and upgrades for Ryu's weapons.Muramasa also gives quests and relates back-stories and other crucial information; for example, he tells Ryu how he can obtain the item required to upgrade his Dragon Sword to its full potential.