In Ohayou, Ibarahime, shy yet diligent high schooler Tetsu Misato starts working at his father's cleaning agency, leading him to the mansion on the hill from his childhood dreams. Within the mansion's secluded garden dwells Shizu Karasawa, the enigmatic daughter of the house, living in seclusion due to a mysterious illness. Chance encounters bring Tetsu and Shizu together, sparking a bond that reveals her isolated existence. As Tetsu grows closer to Shizu, he learns the truth about her condition, leading him on a quest to uncover the person behind the illness. Amidst his developing feelings, Tetsu navigates the complexities of Shizu's supernatural affliction and his own emotions in Ohayou, Ibarahime.