"Prototype" is the fifth part of the Halo Legends anime anthology, out of the 8 episodes that explore the origin and historical events of the Halo universe, in 3D CG and 2D anime format. This episode was animated by studio Bones, and it follows a marine sergeant nicknamed Ghost who leads Hades Squad, a demolition team charged with implementing the Cole protocol - destroying sensitive information and materials during UNSC retreats to prevent them falling into covenant hands. His nickname of Ghost stems from the complete lack of emotion he shows, highlighted in particular by his last mission - in which his entire platoon was wiped out, with him being the only survivor.