Tetsu Misato, a shy yet diligent high school student, takes a position at his father's housekeeping agency, finding himself assigned to the hilltop mansion he watched from afar as a child. Hidden deep within the mansion grounds is a garden and a solitary structure, where Shizu Karasawa, the enigmatic daughter of the household, lives in seclusion. While cleaning near the building, Tetsu encounters the mysterious girl, and upon returning the following day, they rapidly become acquainted. Shizu discloses that she is restricted to the building because of an unidentified illness, having been without human contact for years. As their meetings continue, Tetsu's emotions toward Shizu deepen—yet when he comprehends the true extent of his feelings, he confronts the actual nature of her ailment. Ohayou, Ibarahime tracks Tetsu as he seeks the genuine Shizu beneath her supernatural state—motivated by concern for her and for his own feelings.