When my last relatives were also infected, I began to survive alone in this world full of dangers. I did the same thing almost every day, looking for food and avoiding hordes of half-dead people. I don't remember how long I struggled to survive. Until that day, the fortress that had been tightly sealed after the virus outbreak once again opened the door that had not been opened for many years. At that time, I did not know that this fortress turned out to be the last harbor of human civilization and was inextricably linked to me...