In the spring of 1998 in Yomiyama, Kouichi Sakakibara is set to begin school but is confined to the hospital with a collapsed lung. During his hospital stay, he encounters Mei Misaki, a mysterious girl in his new school's uniform. As Sakakibara eventually joins Yomiyama North Middle School, he is perplexed by his classmates' disregard for Misaki, treating her as invisible. His attempts to unravel this enigma are met with escalating oddities in his peers' behavior. As students in Class 3-3 meet untimely demises, Sakakibara starts suspecting a chilling connection between Misaki and the unsettling fatalities.