A live-action adaptation of the popular doujinshi "Cuckoo's Nest" by Minamihitogakushi! A stepmother named Miki (Mizuki Yayoi) appears in a home where a father and son live together. The son Mahiru feels uneasy in the presence of this young and beautiful woman. Mahiru is troubled by the distance between him and his "mother," but Miki, as a woman, approaches him and tries to have a physical relationship with him, saying, "If you don't accept me as your mother..." Before Mahiru knows it, his Kokoro is drowning in the ambiguous and sweet relationship between "mother and child" and "man and woman."