Following a global memory wipe by a mysterious force, chaos erupts as society crumbles without identities or language. Wandering into a military facility, a young man meets Johnny, the sole individual with retained memories. Dubbed Wataru by Johnny, the man learns from him before Johnny's demise. Determined to seek others like him, Wataru encounters Sophia in San Francisco, a reticent woman bound for New York. Together, they traverse America, unravelling the fate of humanity and the true meaning of being human.