Volume 12

Time for the Grim Reaper (『死神』の時間) is the twelfth volume of the Assassination Classroom manga.

Publisher's Summary
Mr. Karasuma gives the 3-E students superpowered uniforms…with great results. What amazing feats will they perform in their snazzy new outfits? Then, Mr. Karasuma gives Ms. Vitch a bouquet for her birthday…with disastrous results. Next, a 3-E teacher is kidnapped by master assassin the Grim Reaper, who threatens to kill his hostage if the students tell anyone. Their rescue attempt goes horribly awry, and soon they are the ones in need of rescuing! But at what cost to the world…?