Eggman has lost again. He retreats to his lab and, in frustration, channels the residual Chaos Emerald energy from his last defeat into something experimental—something that damages the balance between dimensions. Sonic's world begins to overlap with a parallel universe: the home of Ashuro, a young badger who is completely unprepared for what is happening to her world. With both universes collapsing into each other, Sonic and Ashuro realize they have to work together to separate them and get each of them home.