Requiem For The Living (Kawoshin AU)

In a dystopian world scientists have created a drug that can temporarily kill you. After they give this drug to "volunteers" with special machines they can monitor them in the afterlife in their effort to answer humanity's number one mystery: What comes after death. Though experiments keep failing with the volunteers waking up with no memories, traumatized and shocked to the point they never talk again. Shinji and Kaworu are different though, they didn't wake up at all. At the same time everyone thinks they are dead and never coming back, they desperately try to find a way to come back from the spiritual world they ended up together.