Torabishi Takuji hears a noise he has come to label "grey". He doesn't know the true nature of the noise, and finally has started to lose the ability to discern between "delusion" and "reality". "Delusion" and "reality", "life" and "death". Caught between those, he has started to seek proof that he "lives in reality". A stepsister that hides things from her brother. An energetic childhood friend. A beautiful girl with a coolness in opposition to her cute appearance. A mysterious classmate with an conduct soaked of the occult. A beautiful female teacher that lavishes her adult charm. A male student of whom several dark rumors talk about... These different characters will see their psyche cornered to the limit. This is their story.