A Wind Named Amnesia(1990)

Kaze no Na wa Amnesia

The wind blew it all away... can humans get it back?

Are we shackled by civilization? What is a human being, when freed from the pressures of society? A Wind Named Amnesia explores Earth after a mysterious wind blows away all of humanity's memories and reduces people to a more primitive state. Through certain circumstances, Wataru has relearned how to speak and think, and now is determined to find out just what remains in the wake of the wind. Joined by a strange woman named Sophia, the two of them set out on a journey across what was once known as the United States of America. Along the way, they will witness the true nature of man, and just what it means to be human.

(Source: Discotek)