The world has been devastated by sudden dimensional portals opening and monsters from other worlds crossing over wiping out great portions of humanity. Humanity survives only because higher beings start granting certain people their powers and abilities in order to fight back against these monsters. Years after humanity has come back from the brink of destruction the twins Mitsumi and Toshi are separated, a few more years down the line and Mitsumi holds a powerful position in the military whilst Toshi goes to college.

One day she gets a phone call, Toshi is missing.