“A book that I will never re-read” - Gokudo Yakudzaki. Secrets exist, even if friendship is at the most trusted level. Among friends, there is always a person who is hiding something. In this story, 7 friends will investigate the murder of their friend Eri Tsuchiya. The investigation suggests that the killer is in the company of teenagers; interrogations do not give the desired results. Therefore, the police decide to take a risk by closing the school, leaving only seven teenagers in it. Investigators give the schoolchildren 24 hours to confess who was involved in the murder. Despite the difficult situation, Kazuko Dazai tries to remember what really happened between her and Tsunaki Matsushita at night in a tent three years ago. The teenagers face a test for strength. Death chooses the weak. Seven schoolchildren must pass all the tests that their dead friend came up with. Fortune is not always on the player’s side; deadly adventures await teenagers in the secret passage.