Dead Mount Death Play, Vol. 12 (manga)

As Polka ascends the stairs to the abandoned hospital's rooftop, he hears voices crying out in pain. He soon learns that these voices belong to the spirits of long-deceased patients, bound to this world by their lingering regrets. More specifically, the basement seems to be the primary source of their discomfort.

With no way of getting any further answers from the spirits, one question remains: what lurks below…?