The Hand Crank is a key item found and used in "The Path To Zarkhan" chapter. During this chapter Ryu will find a half submerged sunken small ship, where is he swims into the ship's submerged lower section he will find the Hand Crank. Once obtained Ryu can attach it to the reel on the top of the ship, where turning the crank will open a second small area inside the ship with another key item. This other key item found will be the Oxygen Cylinder in the original Ninja Gaiden and Black, or the Key Of Triton if playing Ninja Gaiden Sigma and Sigma Plus.