Iron Knight

Iron Knight summary:

Tsubasa Teppei, a young boy, wakes up in the middle of the street to discover that the world has gone to hell, with no memories after he had gone to school earlier that day. A strange epidemic appeared that transformed many humans into mindless monsters called Goblins. Some of these Goblins have retained their human minds, but not their human morality. It seems that Teppei may not necessarily be normal either. Does he have what it takes to protect the people that he cares about?