Two beautiful and otherworldly girls went to the lake together at night to enjoy the moonlight. One of the girls accidentally fell out of the car and was seriously injured. Detective Kiba Osamu, who accidentally took the same bus to get off work, took over the case despite his exhaustion, but unexpectedly discovered that the relative of the seriously injured girl was an actress he had been secretly in love with for many years. On the one hand, Kiba forced himself to suppress his inner emotions, but on the other hand, he was also involved in a difficult case. After the seriously injured girl was sent to a box-shaped building, she disappeared out of thin air in front of everyone... The third-rate magazine "Monthly True Crime" for which the writer Sekiguchi occasionally wrote, was investigating the dismemberment murder case in Lake Sagami. Editors Toriguchi and Sekiguchi went to the scene to investigate, but they got lost on the way and stumbled into a strange box-shaped building... The girl who disappeared from the hospital bed, the Sagami Lake dismemberment murder case, the Kiba and Sekiguchi where the case was pursued, and the strange box-like building, what is it that connects them? Do monsters really only exist in the human heart?