Kabanata 1: ch.0 (Explanation of this story)

Let me explain how the hero ranking system works. Heroes are categorized into five ranks: D, C, B, A, and S. The D rank is reserved for the Recovery heroes who use advanced technology to heal injuries and ensure a speedy recovery for civilians. The C rank includes supporters who create various weapons, armor, gadgets, gears, items, and equipment. Sidekicks make up the B rank; they assist the top pros in their missions. A rank is comprised of rescue heroes who are responsible for saving lives and rescuing those in need, even if it means fighting humanoids. Finally, the S rank consists of the top pros who risk their lives to save others and combat higher-level threats than the humanoids.