Darkness Sign: Demarcation

A Spell Card of Rumia from the world shrouded in scarlet mist. This attack divides the world into darkness and light. Light is the absence of darkness, and darkness is the absence of light... is a common misconception. In the boundary between light and darkness, infinite shades of gray exist. Furthermore, while perfect darkness (a total lack of light) can exist, perfect light (a total lack of darkness) is difficult to achieve. That's because filling a space completely with light is nearly impossible. At least a little darkness persists no matter where you are. It's, therefore, difficult to define the boundary between light and darkness when you stand in the light.