“The Water That Falls on You from Nowhere,” by John Chu
Appeared here on Tor.com on February 20th, 2013 (“This short story was acquired for Tor.com by consulting editor Ann VanderMeer”); edit: won the 2014 Hugo for Best Short Story!; recorded here for Escape Pod episode 459, August 21st, 2014
The supernatural device in this story is just as unexplained and arguably as unnecessary as the one in “The Paper Menagerie,” but it feels perfectly natural to me. It probably helps that the water is important to the plot. But really, the whole story feels natural, like something written spontaneously in one sitting.