The Netherworld Challenge is a small "island" within The Underworld in Ninja Gaiden: Dragon Sword . Much like the Abyssal Underworld, there are various skeletal figures in the background. Ryu Hayabusa must fight an onslaught of enemies and Fiends within. The only way to escape this area is to kill all the enemies in this portion of Hell. Once defeated, a Wood Amulet will appear. The challenges can be found through portals in the Stone Circle Cove between the different locations in Ninja Gaiden: Dragon Sword. These portals will glow yellow.