Wishing Stairs

A staircase leading to the dormitory of a remote boarding school usually has 28 stairs, but every so often there appears to be 29. When someone steps on the mysterious extra stair, the horror begins.

Wishing Stairs is a 2003 drama horror movie directed by Jae-yeon Yun, starring Park Ji-yeon, Jo An, Park Han-byeol. It holds an IMDb rating of 5.8/10 from 3,492 votes and runs 1h 40m.