Clinging into an unfinished letter published by her recently deceased dad, young mo-mo goes into Shio's remote Japanese island with her mommy by Tokyo. She starts to research her new habitat, learning their customs and routines and meeting with local kids. But, it isn't long until the island is cropped around by several events. Orchards are observed ransacked, precious trinkets start evaporating and, most bizarre of all, each morning after her mother leaves for work, mo-mo hears strange mumblings coming from the attic of the house. Annoyed by those creepy goingson and her mother's refusal to think them, mo-mo embarks on a strange and unnatural adventure to discover the source of the mischief, that leads her to a trio of annoying imps: the flatulent lizard Kawa, the child like Mame and also their hulking ogre pioneer Iwa. Mo-mo also learns that her trip to the island is in a way.