In a small mountain hospital called Mihara Hospital, a young girl transfers from another facility. Her name is Sasano Yuuna—a frail girl who’s been in and out of hospitals her whole life. "Ahh, we’re here. So this is Mihara Hospital…" "It’s a hospital in the mountains, perfect for recovery. I’m sure you’ll feel better in no time, Yuuna." The one responding is a nurse accompanying Yuuna—Tachibana Misaki. As Misaki finishes the transfer paperwork and prepares to leave, the hospital’s doctor, Mihara Ayaka, stops her. "I know this is sudden, but if you’re willing, could you help out here for about a week? I’ll contact your hospital and explain." Thinking it might help Yuuna adjust to the new environment, Misaki agrees without hesitation. —Unaware that this decision would lead to a tragic tale. This remote hospital had already been taken over by mysterious tentacle monsters. Trapped in an inescapable, confined space, the two are violated and tormented— Will they find despair, or something else…?