Ansatsu Kyoushitsu

Synopsis

The students of Class 3-E and Class 3-A fight against each other to slay the problems before them, with the Class 3-E students benefitting from Koro-sensei's unique teaching methods. When the results are revealed, three of Class 3-E's students get top marks over the Big Five, winning their wager over them, but Karma ends up losing to Gakushu due to being too overconfident and not studying hard enough. With three tentacles earned already, the students earn four more tentacles for scoring top marks in home ec, resulting in a total seven over all. Having won the wager as well, the class decide to use their reward, a summer vacation at an island resort in Okinawa, as the venue for their assassination.

(Source: Wikipedia)