Suicide Circle: The Complete Edition tells in four different chapters the story behind a fictional mass suicide that takes place on the Shinjuku Station in 2002, on which 54 high school girls throw themselves in front of a train. This event unleashes in Japan -- and soon after, in the world -- a chain of suicides that seems endless. Police officers try to stop it and understand why this is happening, and after several events they find a connection between the suicides and a website, haikyo.com, that belongs to a mysterious organization called Family Circle.
Through this website, Family Circle enrolls young people and incite them to run away from home to serve the Circle "family rentals", a service that the organization provides to families who lost relatives to suicide. Parallel to this, alongside the police's quest, the book also follows the story of one of Family Circle's new members that witnessed the mass suicide, Noriko Shimabara, and how her own family slowly falls apart to the suicide wave, while her father tries to "rescue" her from the Circle. In the end, all the pieces come together as the true meaning behind haikyo.com is revealed.