Thirteen students in all in Year 10, Class Black. Twelve assassins, one target. The first to kill the target will get whatever they want. As one of the assassins, Tokaku Azuma joins Class Black and begins to size up the competition.

All 13 students are now assembled and things are about to get serious. But one of them thinks she can jump the gun and beat everyone to the prize.

Tokaku switches sides to Haru, but the game is still on and the first official Class Black assassination attempt is made.

It's three straight days of testing for Class Black. While Haru is intent on passing those tests, another one of the girls is intent on killing her.

Class Black prepares to put on a production of "Romeo and Juliet" for the school festival and another assassin tries her luck.

Class Black puts on "Romeo and Juliet" in front of a student audience, but with so many deaths in the play, maybe one or two will be real.

Another assassin tries her hand, but this one proposes a game with rules that will give Haru and Tokaku a chance to beat her fair and square.

The field has been whittled to four assassins. With classes done and a typhoon closing in, Haru and Tokaku are in for a harrowing evening.

Tokaku faces Isuke and her own inner demons, while Haru desperately tries to stay ahead of Shinya.

With Class Black down to four students, Tokaku and Haru face off against the person they consider to be their final opponent.

The truth about Class Black is revealed, and Tokaku and Haru must grapple with the implications of this new information.

Now that Tokaku has delivered her advance notice, the three remaining members of Class Black have one last assassination attempt to sort out.

Unaired episode 13 of Akuma no Riddle was previewed at a screening in Tokyo City on November 22, 2014 and released with the seventh Blu-ray/DVD volume on December 17, 2014.