The story is set in a fictional Germany and centers around the outbreak of bio-mechanical creatures named "Demoniacs", who rise from corpses and attack people mindlessly. All the while, a number of human-turned-Demoniacs appear. Some use their powers for good whilst others for evil. One will rise above all other Demoniacs to become the "Blassreiter".
Blassreiter (2008) is now streaming with subscription on Crunchyroll