Akuma no Riddle: Riddle Story of Devil Vol. 4

The Class Black is comprised of thirteen students, twelve of whom are assassins. Their prey, Haru Ichinose, an upbeat girl who vows to survive school. Enter Tokaku Azuma, a killer who transfers from another school to kill Haru. What should have been a routine hit turns into a more complicated affair as Tokaku is unable to pull the trigger on Haru.