Chapter 37

Art Time (アートの時間, Āto no jikan) is chapter 37 of the Assassination Classroom manga.

Short summary
The students change into summer uniforms as of July 1st. Sugaya appears with a henna tattoo, to which Korosensei enthusiastically asks for one. Sugaya attempts to kill Korosensei with tainted henna paint, but fails. Nevertheless, he re-draws with normal paint on Korosensei's head, as well as on the arms of the students. Irina enters the class in horror, while Korosensei wants to try drawing a pattern himself. Irina refuses but conveniently knocks herself out, allowing Korosensei and Sugaya to compete drawing on her. Afterwards, Irina wakes up and walks off quietly, returning to murder the entire class with real guns until stopped by Karasuma.

Long summary
As it is July 1st, the students of class 3-E change into summer uniforms. Okajima enjoys staring at the girls with their more-exposed skin as Nagisa watches him on weirdly. With a neutral face, Korosensei tells Okajima not to let it distract him, despite reading an erotic magazine himself, to which Okajima calls him out. A student walks into class, realizing he forgot everyone is wearing shorter sleeves starting today. The entire class, including Korosensei, stare in shock as Sugaya reveals a large tattoo across his left arm. He claims he didn't want his arm, sealed by the gods, to be revealed.

Kurahashi admires the art, realizing it was painted on his arm. Sugaya reveals it to be a henna tattoo which can't come off for about a week after it's set on. Karma recalls the tattoos coming from India, claiming his parents love the country and come back with the tattoos everytime they travel there. Having just read a large pile of books on delinquents, Korosensei is relieved Sugaya isn't turning into one, to which Kayano stares and recalls that he always worries about these things. Sugaya offers to draw Korosensei a tattoo, to which Korosensi exclaims gleefully for one. Watching Sugaya prepare the paint, Nakamura compares the material to melted chocolate. Sugaya begins his first line as Korosensei expresses having always wanted to get a pseudo-tattoo. Suddenly, the whole class and Korosensei become horrified as they watch his face melt in front of their eyes. With Korosensei having ran off, Isogai realizes that Sugaya grounded up some anti-sensei bullets and mixed them into the henna paint. Okano claims that even though Korosensei let his guard down, he'd have to sit still long enough to get killed by the paint. Having recovered from the tainted paint, Korosensei praises Sugaya's idea, but starts to cower and cry after having wanted him to draw a cool design. Sugaya immediately apologizes and offers to draw one on him with normal henna paint this time.

Walking towards the classroom, Irina feels refreshed with her increased summertime exposure. She opens the door to greet everyone only to scream in horror after seeing the entire class with henna tattoos all over their arms. Sugaya claims the entire class wanted their own tattoos after seeing his. With patterns around his academic cap and on his cheeks, Korosensei explains that the pigment will set in after awhile once the paint is removed and claims he can't focus anymore from being so excited. Irina exclaims that he's supposed to be the homeroom teacher. Having watched Sugaya draw, Korosensei wants to try drawing them too. Sugaya allows him, but recalls there aren't any more blank canvasses to draw on. Both then stare at Irina and agree in unison to use her, to which Irina starts to flare up. She accidentally slips on a pack of paint on the floor, tripping and crashing her head against the wall, passing herself out. The students agree to let her rest for awhile, while Korosensei and Sugaya agree to a competition. Okuda admires Sugaya for having let everyone into his new art style quickly.

It is revealed that in his second year, Sugaya's artistic tendencies got him in trouble, having once driven an entire drawing on the chalkboard in front of everyone's horror. With his poor grades and his artistic talent, he was looked upon as a delinquent. Finding a low score on his test with an elaborate drawing on the other side of his page, Sugaya's teacher scolds him, folding his test into quarters, throwing it back at him, and sending him off to class E. Recalling his past, Sugaya claims she's right and begins drawing on Irina's right arm. After finishing his drawing, the rest of the class admires his drawing, to which Yada and Kurahashi think Irina should be grateful for it. Now wearing a beret and sunglasses, Korosensei reveals what he drew on Irina's left arm: a short manga of a cook deceiving an octopus into giving it a new "coat". The students are shocked at the manga, to which Korosensei claims he is bad at art and fashion ahnd went with his forté instead. The students consider that it's no longer safe to bring her out in public anymore, to which Sugaya claims some consider manga to be a revival pop art too and decides to draw along the manga's borders. The manga ends up looking much more fashionable afterwards. However, Korosensei considers the art too pretty and that it'll make her look smug, and so offers to add something for people to laugh at, to which the students are annoyed at his competitive edge. He draws fake glasses, a mustache and the word "medium-sized" on her forehead. The two continue to alternate between each other, adding new drawings onto Korosensei and even dressing her up with cardboard.

Eventually, Irina comes out ranging from Sugaya's more elaborate drawings, including a heavily stylized word "BITCH" written on her left arm, to Korosensei's more simplistic doodles, such as drawings of a giant peach and a moocher on her left leg, all inside a cheap samurai uniform. Feeling regrettful, Sugaya claims there is a way to remove it, but it'd be painful, to which Korosensei hopes Irina will just be happy with it. Finally, Irina opens her eyes. She quietly checks herself out and leaves the classroom. Maehara looks out the door to find Irina returning all monster-like and approaching the classroom holding real guns. She attempts to massacre the entire class, to which all the students run off and Korosensei apologizes for getting into henna while trying to stop her from destroying the class. Sugino tries to hold her from behind, telling her it'll come off if she doesn't set it. Irina is still outraged that her summerwear debut is now ruined. Nagisa laughs it off and claims she wouldn't be so angry if Sugaya did it alone. Sugaya agrees and claims he always used to be irritated that the doodles on the back of his assignments were ignored, but that Korosensei would instead add on to them and even have fun with them, recalling a drawing he made of Rembrandt. He figures it's only natural since doodling should not make him lose points and that everyone is supposed to kill him anyways. Meanwhile, as Irina continues to shoot him, Korosensei admires her and offers her a stick of Pooky. Sugaya realizes the killing ordeal isn't so bad since being unconventional is still considered normal in the class. Nagisa agrees as he watches Karasuma enter the classroom appearing irritated at the quarrel, thus beginning the last eight months to assassinate Korosensei.