Episode 19

Demon Time is the nineteenth episode of the Assassination Classroom anime. The episode first aired in Japan on May 29, 2015.

Summary
Immediately after their summer assassination attempt on Korosensei, a new enemy has appeared. With only 24 hours to save their classmates, the 15 unaffected students must infiltrate the hotel and take that antivirus.

Plot
While Takebayashi and Okuda take care of the poisoned students at their resort, the rest of the class and the teachers arrive at the bottom of the cliff where they new enemy is staying at. The sheer cliff face to reach the unguarded entrance puts Karasuma in doubt as to whether they can successfully infiltrate the hotel. Just as he is about to give in and allow Nagisa and Kayano to deliver the immobile Korosensei, the class start climbing the cliff, to their teachers' astonishment. They state that they have been trained to climb the mountain at the back of the school but have not been trained in infiltration. Seeing the class's resolve, Karasuma firmly takes charge as their mission commander.

Everyone is able to climb the cliff, although Karasuma is unfortunate to carry both Korosensei and Irina on him. At the entrance, Ritsu goes through the final diagnostic of the hotel. The elevators are out of the question so they need to take the flight of stairs all the way up to the top. This is tricky itself as the stairs ae not at the same location as Chiba notes that the layout had been planned to counter terrorist invasions. Once inside, the class make their way to the reception area. With the lobby heavily guarded, there is no way to slip past to the second floor unnoticed. With Karasuma out of options, Irina casually states to just walk through, much to everyone's surprise. She walks out to the lobby, acting as a tipsy pianist who arrived a week early and asking the guards to watch her play the piano. Her music and body language seduces every guard to her, and away from the class's position. With concealing hand signs, Irina tells the class that she can buy them 20 minutes and to go. The class follows through unnoticed. Safe for now, they discuss how Irina has surprised them which Karasuma explains that is the mark of a professional infiltrator.

At this point the floors are less guarded and the students can act as the hotel guests. Although some question whether seeing a bunch of teenagers would attract attention, Korosensei assures them that the kids who stay here are rich and use their innocence to carry out illegal activities to act cool. Continuing their way through, the smaller number of guards causes Terasaka and Muramatsu to act cocky and charge forward ahead of Karasuma. As they prepare to pass by another guest, Fuwa shouts out to the two boys to stop. In one swift movement, Karasuma pushes the boys back as the guest triggers a cloud of gas. The gas engulfs Karasuma, who breathes in a tiny amount while the guest already had a bandana around his face. Fuwa recognises him as the butler that served the students drinks when they first arrive, and question him whether he is the poisoner. He neither confirms nor denies this but Fuwa deduces that he is - the only times the whole class ate and drank together were immediately after entering the hotel and during dinner. However since two were editing the film during dinnertime, this left out the drinks which Fuwa concludes were spiked with poison. Nagisa and Kayano are impressed by this, though not enthusiastic to hear that Fuwa's detective skills were gained from reading shonen jump manga and subtle product placement.

The guest reveals himself to be a hired hit man and sees that Karasuma has been affected by his gas. Noting that the class do not intend to negotiate for the antivirus he turns to leave, but sees all the exits blocked off by the students. Karasuma mockingly states that he should have ran to tell his boss instead of talking to the group. The hit man prepares to finish off Karasuma but is swiftly kicked unconscious by the latter before he succumbs to the gas. Isogai supports Karasuma but with all their teachers incapacitated the students are left to fend for themselves as they make their way up. Korosensei carelessly states that this is how a summer vacation should be, earning himself the students' ire and being whirled around by Nagisa.

The group reaches the scenic floor and see a lone man leaning against the glass window. They come to a halt and attempt to think up a plan to no avail as there is no other way around. Suddenly the man cracks the glass with just his bare hand and calls them out with each sentence he says ending with a 'hm'. The group comes out of their hiding spot though more curious about the man's verbal tic. Karma fearlessly asks him about it which the man answers that it is learnt from studying the samurais, admitting that he is a foreigner. Seeing that Karasuma had been incapacitated earlier, his will to fight has gone and proceeds to call his boss by radio. However Karma destroys the walkie talkie with a pot plant, and goads the hit man to fight him instead of running away from a group of school kids. Karasuma tells Karma not to be reckless though Korosensei sees that the boy's chin is down. Before his chin was up that signifies him looking down upon others, but the crushing blow from the recent exams forced Karma to lay low. With his chin down, Karma is now more serious but still retains his attitude. Both Karma and the hit man prepare themselves for a duel as the episode ends.