Forget Me Not: Aconite

The world is very different when the dead start walking, and people tend to forget their pasts in the process. But not everyone can do that. When Kaden reunites with his ex friend of 8 years, who seemingly has no memory of him at all, will he be able to move on from the past and survive the hellish world with her in unison? Or is the past they had too important to be forgotten?