Volume 15

Time for a Storm (嵐の時間) is the fifteenth volume of the Assassination Classroom manga.

Preface
''Ever caught yourself screaming, "I could just kill that teacher"? What would it take to justify such antisocial behavior and weeks of detention? Especially if he's the best teacher you've ever had? Giving you an "F" on a quiz? Mispronouncing your name during roll call...again? How about blowing up the moon and threatening to do the same to Mother Earth—unless you take him out first?! Plus a reward of a cool 100 million from the Ministry of Defense! Okay, now that you're committed... How are you going to pull this off? What does your pathetic class of misfits have at their disposal to combat Teach's alien technology, bizarre powers and...tentacles?!''

Publisher's Summary
Several secret pasts are finally revealed this volume: The tragedy that led Principal Asano to develop his harsh—some would say brutal, sadistic and inhumane—pedagogical methods, the relationship that gives one 3-E student a personal motivation to assassinate her teacher, and even Koro Sensei’s origin story! Will the students be more or less motivated to assassinate their teacher after they know his former secret identity? And what lengths will shy Nagisa go to in order to rein in the student who wants to get revenge on Koro Sensei? Also, it’s time for…lunch theater! Which member of 3-E will be the star?