The Shadows of Who We Once Were Vol. 8 (Kodansha, 2023)

Twenty-seven former classmates of Shinozuka Elementary School year 6 class 2 gathered at their elementary for a reunion but was locked into the building, unable to escape. The man behind it is Mikio Yumesaki, with the sole purpose to test the goodness in humanity under extreme circumstances... Thus begins an immoral experiment to expose the good and evil of humanity at a fake reunion. Two years after the 52 hours of confinement, the surviving students meet again. And standing on the land where they lost everything, they make a vow in the face of the many sacrifices and countless sins they've committed. They swear to never allow themselves to be swept away by anything and to take a step forward to live their lives...