Death Bell (2008)
Death Bell is a 2008 South Korean film. The only Korean horror film released over the summer of 2008, it is the first feature by former music video director Chang (real name Yoon Hong-seung), who also co-wrote the screenplay. Death Bell stars Lee Beom-soo in his first horror film role, and K-pop singer Nam Gyu-ri in her acting debut. Set in a Korean high school, the film's native title refers to gosa, the important midterm exams that all students are required to sit.
More at Wikipedia.