The Shadows of Who We Once Were Vol. 6 (Kodansha, 2022)

27 former students of the Shinozuka Elementary school have gathered for a reunion only to find themselves being locked in the old school building. The man behind this crime is none other than Mikio Yumesaki, with a goal to test the goodness in humanity. On the second day of their 52 hour-long experiment, the heinous crime claims its tenth victim. For power, for revenge, an unknown assailant attempts to rise up and take over the experiments. With their thoughts scattered in confusion, three tragedies occur simultaneously as a young man's ""good"" turns to ""evil.""