is a Japanese
mystery horror novel by
Yukito Ayatsuji, published on October 29, 2009 by
Kadokawa Shoten. The story focuses on a boy named Koichi Sakakibara who, upon transferring into Yomiyama Middle School and meeting the curious Mei Misaki, finds himself in a mystery revolving around students and people related to his class falling victim to gruesome, senseless deaths.