Tokeijikake no Ley Line -Tasogaredoki no Kyoukaisen-

In a mysterious boarding school deep in the mountains, a giant clock tower splits day and night into two separate worlds. New student Michiru accidentally breaks an expensive statue on his first day, and to pay for the damage, he and the boy responsible are forced to work for the school's “Bureau for the Investigation of Special Affairs.” Deep in the underground library, a cold-eyed girl reveals the truth: magic is real here. At the toll of the clock, the “Realm of Night” emerges and merges with the school. The Bureau’s job is to handle the supernatural incidents that follow. Now, Michiru must protect the school from troublesome magical items called “Mists”...