Bloodthirsty Weapon

This is a story set in another universe, known as the Mirror Four Universe or the Reverse Four Universe. Its civilization, history, and other aspects are both similar to and different from those of the Zero Universe we live in. Billions of years ago, thirteen divine artifacts forged by the souls of the stars all fell to Earth. These bizarre weapons grow stronger for a short time when stained with blood. They are the most powerful kind of weapon from ancient times to the present, and people call them Bloodthirsty Killing Weapons.