My Shadow Demon System

Scientists have discovered a backdoor to a parallel universe called Karos. After accidentally opening one, the world turns chaotic with monsters of all kinds surging through. The weak and powerless Leo Naro falls victim to a beast attack and is transported to the alternate universe. In a world were monsters now roam and eligible has either a power stone or a Rune stone to protect themselves. Leo has something quite peculiar THE SHADOW DEMON SYSTEM < You must kill to consume shadows after 48 hours <