The Jumping-into-Pool Evil Spirit

In the summer of their third year in middle school, Miyuki drags Hajime to swimming school so he can finally learn, but they stumble upon drama between two divers and former best friends competing for a place at a prestigious high school. An accident happens, putting the wealthy, privileged diver into a coma. Was it down to the rumored "evil spirit of the diving pool"? Hajime suspects a more down-to-earth evil and investigates!