The land of Rising Dusk exists in a permanent in-between hour—neither fully day nor fully night—and its inhabitants are the Yokai, the spirits and demons of Japanese folklore who stir whenever the light is uncertain. When Tamako, a young girl, accidentally glimpses one of these creatures, she crosses a boundary she didn't know existed and finds herself trapped in their world. The only path home leads to a strange new mountain visible on the horizon, reached through terrain populated by ghosts, ghouls, and the specific rules of a world that runs on mystery.