For those needing a refresher, follows Chika Amagi , a high school girl sent to the notorious Haguro Island Prison . In this world, "Medusa Syndrome" turns ordinary girls into ruthless killers by activating murderous split personalities based on famous serial killers. Chika, whose "base" is the infamous Henry Lee Lucas, must navigate a lethal environment where inmates are experimented on to become elite assassins. What to Expect in Chapter 291