X-0 is an experimental Imperial weapons team created and led by Dr. Heinrich Belgar that fought in the Eastern Front of the Second Europan War. They appear as the main antagonists in Valkyria Chronicles 4.
Infantry from X-0 can be identified by their black armor and purple/gold uniform.
X-0 is the codename for an experimental weapons team founded by the head of Imperial Science Board, Heinrich Belgar. Because it was officially non-military, this special task force did not answer to the Imperial army's chain of command.
To maintain the Empire's technological advantage over the Federation's armies, the Emperor himself granted Dr. Belgar command over a team of elite troops and authority to conduct weapon testing by intervening during military actions.
Though many Imperial officers opposed the science board's unchecked power to interfere with army operations, they had no real jurisdiction over X-O's actions.