The Passing Hour

the rules of life and death have changed as we know it. It is no longer "natural" to die at just any time. Instead, there is a designated time of day for death: The passing hour. No one knows why this is happening, but it slowly becomes accepted as the new way of life over several hundreds of years. People had stopped attempting mass suicides and riots to test the boundaries of that rule. If you got fatally wounded, you had to live with that wound until the passing hour.
Life carried on this way, with no one knowing why it became like this. But now, the truth is going to be revealed.
This story goes back and forth between a boy, who is the main character, and the last grim reaper.