Spring Showers, Death's Hour

When the rain falls, death's bell tollsMarcel and Louise are two estranged lovers who are meeting again in their small hometown of Barro after going off on their separate musical tours. As they try to put the past behind them, a strange kind of rain falls on them that melts certain people, attracts demons, and cuts off the town from the rest of the world. What is the cause of this rain and does it have to do with the town in any way?