Two years back, a group of 8 students and 1 teacher from Kisaragi Academy disappeared without a trace. There was no evidence of their disappearance, nor was there any logical explanation. It was as if they'd just up and left, or never even existed.
Now, two years later, a similar thing happened. A group of 7 students, and 1 teacher, all from Kisaragi Academy, all up and left. The city, like last time, brushed it off as an unsolvable case, and left it be. It was like they never really existed.
In reality, they hadn't disappeared, just been transmitted to a different dimension. A nexus of closed spaces, closed spaces, and more closed spaces all in a sea of space. This hell took the place of Heavenly Host Elementary, a school with more despair to its name than any Shakespere play you could think up. They were divided into different closed spaces, in different time dimensions.
They could hear eachother, see what the other had left behind, but never meet a person in another dimension. The g