Assassination Classroom, Volume 6, Swim Time

The 3-E students discover that Koro Sensei's greatest weakness might be a common substance. Will they be able to use it to assassinate him while he helps Meg, formerly of the varsity swim team, with her greatest weakness? The next assassination attempt, implemented by Terasaka, is more elaborate but endangers his fellow students. Can he save them without saving his target? Then, the top class at school, including Principal Asano's son, conspires to prevent 3-E from ever rising closer to the top!