Akane is hospitalized for a brief stay and placed in a room shared with a young girl who has been in a coma. On the first night, the girl appears awake—standing beside the bed and staring. The two of them have somehow entered the coma patient Yui's inner world together: a vast and intricate space that grows stranger and more dangerous as they descend through it, its surface beauty concealing truths that neither of them was prepared to find.