S1·E45 The Malevolent War God! Mars and Ludwig!

Kouga finally reaches Mars' location, determined to stop him. As the War God deflects his attacks and counterattacks, Eden arrives in time to save Kouga. Mars then reveals to the true story from the days when he was known as Ludwig, a normal human who sought revenge for the death of his beloved wife, Misha. He deflects Eden's attacks before removing his mask, revealing himself as a human no longer.