Houkagogakari

Houkagogakari summary:

When the clock strikes midnight, we're trapped in "After-School." In that world, there's no right answer, no end, no "game clear." There’s only our lifeless bodies, stacking up one by one. One day, Kei Nimori, a young elementary school student, suddenly notices his name scrawled on the classroom blackboard, alongside the mysterious words "After-School Duty." Thus begins a dark, midnight fairy tale of several young boys and girls risking their lives to record and contain monsters in a bizarre realm known as "After-School."