It all started from a rumor that the school swimming pool has a ghost in it, Every innocent life can be the victim, especially when you go there at night. The school knows it but keep it quiet, and just simply lock the pool after day time.

But, there always have some brave people which believe or not believe it, and break into the natatorium at night, and meet the horrible creature there and with no return back.

[From Itch.io]