Yeondu High School's construction led to the unbalanced feng shui around the area. It is said that the area used to be a perfect natural landscape before it was built. During the Korean War, the school was a Korean hospital. Many visitors and builders died during the construction of the building that had awakened the power (Qi) of the imbalance of feng shui and the ghosts from the hospital's past, so a geomancer was brought in to construct 5 amulets representing the 5 elements (Wu Xing). He then equally spread them around the school to balance feng shui and resist the spirits, preventing them from interfering with the living.
Source: Wikipedia, "[en.wikipedia.org/wiki/White_Day%3A_A_Labyrinth_Named_School White Day: A Labyrinth Named School]", available under the CC-BY-SA License.