The world did not end with biblical brimstone and fire. Or with a bang. Or an asteroid smashing against the Earth. It came with a flash, and when that bright light faded, everything cease to be.
The main character (of your own naming) awakens to find himself in the Interim, a realm which exists between the old world and the new. Before long, he runs across Mira, an Entede–a metaphysical being sent to aid him. From her, he learns that he’s there to assist those who’ve yet to properly move on. As these lingering humans desperately hold onto memories of their former lives, he must help them come to terms with their existence, all the while learning about the reason for his own situation.