In 1972, Misaki, a popular student of Yomiyama North Middle School's class 3-3, suddenly died partway through the school year. Devastated by the unexpected loss, the students and teachers behaved like Misaki was still alive, leading to a strange presence on the graduation photo. In Spring 1998, 15-year-old K┼ìichi Sakakibara transfers into Yomiyama's class 3-3, where he meets the peculiar Mei Misaki, who is seemingly ignored by her classmates. The class is soon caught up in a strange epidemic, where its students and their relatives are caught up in mysterious deaths. Learning these deaths have something to do with the Misaki of 1972, it is up to K┼ìichi and Mei to discover the cause of these mysterious deaths and figure out how to stop it before it puts an end to them.