Toshiryô densetsu Yûko (2011)

Ten years ago, a young girl was found drowned in a swimming pool. A series of strange events occur at the now-closed school. One day, 10 classmates, including Kane Nojima, a graduate of the school, gather in the there and learn that their former teacher has committed suicide. It was 10 years ago, and the teacher's death follows the drowning incident. The suicide note he left only says "behind the mirror," so Nojima and his classmates investigate the school's mirrors in detail.