Hikiko-san vs Sadako

Two high school girls are daily and cruelly harassed by Risa and the other students in their class. One of them is going to invoke Hikiko san - a woman who died as a result of bullying, who now haunts the rivers and peri-urban areas of Japan. Is it real, or is it just a stupid urban legend?
At the same time, Risa will sink her body in a well after a session of hypnosis that went wrong: she will end up possessed by the spirit of Sadako!