The students are at the school, some of the students hunting for bugs to make a bit of money before vacation. Another student, Okajima Taiga, has trapped Koro-sensei with a bunch of porn. Unfortunately, the assassination is thwarted when Koro finds a miyama stag beetle.
Lovro, Kurasuma, and Irina decide to train the students while Koro-sensei is away. They discuss how to take down Koro during their vacation. Nagisa asks Lovro what makes a good assassin and it told about an assassin known as the Reaper. If one fails to assassinate their target, he is said to show up eventually.
On the island, while one group spends time with Koro, the other groups make preparations for their assassination. The students manage to get Koro to shed his skin and get him seasick as ways to weaken him and the episode ends with the students getting ready to turn on a movie for Koro (assumably porn since it’s his weakness).
My favorite part of this episode? I really enjoyed Karasuma throwing Irina into the water. I also loved seeing all of the students in cute casual clothes.