Elegant Yokai Apartment Life, Volume 19 (Elegant Yokai Apartment Life #91-95)

Hase's sister Migiwa, an athletic girl full of energy, is in the hospital with an unknown, but serious stomach ailment. The whole Hase family is alarmed, but when Migiwa tells Yushi about the nightmares she's having - featuring a demon that slowly comes closer to her, night after night -- Yushi suspects that the cause could be supernatural.