The narrative is set in a universe where countless parallel worlds are known to exist. A connection, termed "Prism," always links the modern world to these parallel realms, occasionally allowing energy and matter to pass through. One day, monsters called "Eight" emerge from a parallel world and start attacking. Humanity launches a counteroffensive using a power named "Skuld," which taps into the power of tomorrow. The government recruits Skuld users into an army dubbed "Norn," yet the Eight continue to cause devastation over the years. Subsequently, a boy named Asuma, capable of wielding an ancient weapon, is discovered.