A plane has crashed during its flight towards the Sphere, a mental hospital, and Fuyugawa Kokoro was one of the survivors in this accident. She did not know if it was a dream or what, but she remembered waking up in the Sphere after the accident. Due to intense confusion and post trauma experiences, she fainted again. When she woke up the second time, she was located in a shelter somewhere near the crash site.
One of the three survivors Kokoro met in the shelter was Yukidou Satoru, who was chased by a strange shadow across the Sphere when the plane crashed. Being caught off guard on the clock tower, the man fell, however, when he woke up, he was in the same shelter.
To escape and clear up the incident, they have to find a way out of the unclosed space.
