Whispering Corridors

Whispering Corridors is a Korean horror film directed by Park Ki-Hyung in 1998 about a series of unexplained murders committed by a ghost. Eun-Young, a former student turned teacher, investigates the murders after Mrs. Park, a fellow teacher calls her about Jin-ju, a former friend of Eun-Young's. Three students, Ji-oh (an art student), Jae-yi (a shy student), and Jung-sook (a strange and unpopular student), doing morning janitorial duties find her body hanging from a tree. Although her death looks like a suicide, rumors fly around the school that Jin-ju, an unpopular student who died years ago is back to take revenge on the teachers who tormented her. Eun-young and the three students get caught up in the dark secrets of the school and must stop the ghost before she commits another murder.

Tropes used in Whispering Corridors include:

Before School Cleaning Duty: The three main characters are assigned to before school janitorial duties and it's where they discover the body of Mrs. Park.
Banned In Korea: The Korean National School Board tried to ban this film on its' release, due to its' themes of student homosexuality, physical and sexual violence committed by teachers, and stress among the students brought among by tremendous pressure to succeed. Fortunately for foreign film fans, these attempts failed.
Boarding School of Horrors: Jookran High School for Girls. Not only to you have to deal with nasty class mates and teachers; it's also haunted.
Driven to Suicide: Jung-Sook, an intelligent but unpopular student hangs herself after being harassed by a teacher.
Ghostly Goals: Jin-ju A.K.A. Jae-yi goal is take vengeance on all teachers at the school because she was mistreated by them. She's a combination of types A and B.
In-Series Nickname: Mrs. Park and Mr. Oh are given by students the unflattering nicknames of The Fox and Mad Dog.
High School: The film takes place in a girls-only Korean High School.
Odd Friendship: Jae-yi (a shy student) and Ji-oh (an outgoing art student) have little contact with each other at the beginning of the film, but quickly become fast friends.
One-Gender School: Jookran High School is all-girls school.
Our Ghosts Are Different: The ghost looks like an ordinary high school student, is not transparent, and walks around in the daylight.
Mauve Shirt: Mrs. Park and Mr. Oh
Psychic Powers: Ji-oh, an art student, is rumored to be able to communicate with the dead. She even conduces a seance at one point before class.
Posthumous Character: Jin-ju. Much of her character is explained through Eun-Young's flashbacks and dialogue.
Sadist Teacher: Mr Oh, A.K.A. Mad Dog. He beats students he disliked and sexually harasses those he likes.
Shrinking Violet: Jae-yi.
Spooky Seance: So-young, one of popular students at the school, convinces Ji-oh to hold a seance to find out whether Jin-ju murdered Mrs. Park. The ghost starts to answer, but is interrupted by a teacher.
Zettai Ryouki: The school uniforms that the girls wear.