When 54 high school girls throw themselves in front of a subway train it appears to be only the beginning of a string of suicides around the country. Detective Kuroda tries to find the answer to this mystery, which isn't as simple as he had hoped.

A teenager named Noriko Shimabara runs away from her family in Toyokawa, to meet Kumiko, the leader of an Internet BBS, Haikyo.com. She becomes involved with Kumiko's family circle, which grows darker after the mass suicide of 54 high school girls.