My homeroom teacher can destroy the Earth. I found out that wasn't a joke a long time ago. By now, it's become completely ordinary. Hike up the mountain path for twenty minutes, arrive at the old school building on the summit, and stare at the blackboard while the yellow octopus-faced teacher says things like "nurdely!" That's the morning of Class E. Class 3-E of Kunugigaoka Middle School. Officially, the "E" stands for "End." The old school building twenty minutes northeast of the main campus, where nobody comes. The twenty-eight of us study both academics and assassination here. Our homeroom teacher, Koro-sensei, moves at Mach 20. Last year, he destroyed seventy percent of the moon. If nobody kills the teacher by next March, Earth will be next. That's why the government put a ten-billion-yen bounty on his head and assigned us the assassination mission. Every morning, the teacher distributes a schedule that includes assassination training time. The equipment shed is stocked with anti-teacher knives and BB pellets, and after school we use them to try to kill the teacher. It's never worked once. Usui Nagisa sat by the window, thinking about such things in a daze. The deep blue twin-tails were tied short, and today too the white shirt's necktie hung a little loose. Holding a mechanical pencil between slender fingers, Nagisa copied the teacher's blackboard notes into a notebook. The androgynous features often got mistaken for a girl. Nagisa didn't particularly mind. Right now, though—— (Again.) A quick glance at the seat next to them. Akabane Karma had his chin resting on his hand, eyes on the blackboard. Red hair. Lazy-looking eyes. That slight upturn at the corner of his mouth. Not panicked at all during class, yet the moment the teacher posed a problem, his hand shot up first. When Karma noticed Nagisa's gaze, he grinned. Nagisa quickly looked away. (I looked again. Why do I keep looking?) This is assassination observation. That's what Nagisa tried to tell themselves. But the words rang hollow in their chest. It had nothing to do with assassination. They just kept looking. Every time Karma stood up, every time he said something, every time he laughed. This is bad. The moment that thought began to form—— "Alright then, time for today's main event!" Tentacles moving at Mach 20 wiped the blackboard clean, and large letters appeared in its place. "Assassination Skills Mid-Term Evaluation." The entire classroom stirred. Koro-sensei held a thick file between his tentacle tips and flipped through it one by one, smiling. The teacher's face was basically yellow. But it changed color with emotion. When in a good mood, it was a vivid yellow like now. When embarrassed, pale pink. When flustered, white. All the students in Class E were used to those color shifts. "Okajima, your concealment of presence has improved. Next, let's work on your shooting accuracy." "Hell yeah." "Maehara, you're still too loud. No matter how close you get, the teacher will notice you that way." "Shut up." One by one, the teacher flipped pages with his tentacles and gave evaluations. Listening to this, Nagisa absently doodled on the edge of their notebook. Circles. More circles. Before they realized it, they'd drawn red circles. Erase them. Eventually, the teacher's tentacle stopped on Nagisa's page. "Usui." The teacher's tone seemed to shift slightly. Nagisa looked up. "Your average heart rate has increased by 7% recently." The classroom fell completely silent. Something cold ran down Nagisa's spine. From the nape of the neck down to the waist, a slow chill. The teacher was still smiling, but the tip of his tentacle twitched. That movement when the sensors were at full capacity. The teacher's tentacles could simultaneously read body temperature, heart rate, and even perspiration levels of any human within a thirty-meter radius. The teacher claimed his "romantic feeling detection accuracy" was "99.7%." That number, which all of Class E knew, felt terrifyingly real in this moment. "Is there something on your mind?" A smile. The yellow face turned toward them. Nagisa checked the teacher's complexion for a moment. Still yellow. Not pale pink. Still safe. But the tentacles were twitching. This was dangerous. "The tension from the assassination attempts... it's just increasing." They kept their voice steady. Kept their expression still. Nagisa's greatest skill was concealment of presence—reducing their existence to the absolute minimum. That skill was being used now to hide emotion. Three seconds. The teacher's face remained yellow. "I see. Be careful then." The tentacle turned the page. The evaluation moved to the next student. Nagisa exhaled slowly. "Hey, Nagisa, you okay? You look pale." "It's nothing." "You sure you're alright?" "[sarcastic] I'm fine." They forced a smile. A proper smile. The work of overwriting a face that wasn't fine at all with one that was—Nagisa had gotten fairly used to that. But beside them, Karma was watching with the corner of his mouth raised. What was so funny? Nagisa faced forward. They completely erased the red circle they'd started drawing in the notebook's margin. --- After school, Nagisa went up to the roof alone. The roof of the old school building in Class E was, to be precise, "a flat roof section." No railing. Sparse trees and mountains spread around it, with the sunset beginning in the distance. The mid-May wind was slightly warm, drying the sweat from climbing up here. The area was roughly sixty square meters. Nobody else was here. Nagisa sat at the edge of the roof and dangled their feet in the air. The outline of the distant mountain was rimmed in orange by the setting sun. Coming here after class wasn't a first. Whenever there was something to think about, they'd developed the habit of coming here. (Let me try.) Using an application of concealment of presence to calm the heart rate. That was Nagisa's goal for today. The matter of the heart rate increase the teacher had pointed out in class was still completely unresolved. If this continued, the next evaluation would be even worse. Close the eyes. Steady the breathing. Inhale once, exhale over two counts. Using the same sensation as concealment of presence, thin out their own existence. Inward, quietly. It seemed to be working. For about three seconds. Karma's profile from today's class floated into their mind. Chin resting on hand. Lazy-looking eyes. And when Nagisa looked over, he noticed and grinned—that face. The heart rate jumped hard. "——" Nagisa opened their eyes. Completely useless. Try again. Close the eyes. Breathing. Steady it. Quietly. (I just have to not think about Karma.) Just don't think about it. Simple. Think about something else. Today's math problems. Yesterday's dinner. Next week's assassination training schedule. ——Schedule, right—how should we coordinate with Karma? There it was again. Just thinking the name made his voice echo in their head. That slightly drawn-out way of speaking, yet somehow sharp. The way he always called Nagisa by their first name, never their surname. The heart rate spiraled out of control. "Haa..." The third attempt was the same. Close the eyes, breathe, and three seconds later the heart was loud again. Nagisa collapsed spread-eagle on the roof. The sky was vast. The sunset spreading slowly. A single cloud drifting past. Completely impossible. The assassination skill was completely nullified by romantic feelings. If the teacher saw this, he'd definitely start the "Romance Deviation Value Lecture." He'd draw a relationship diagram on the blackboard, calculate success probability, and distribute it to the entire class. Anything but that. "Maybe I'm just not cut out for liking someone." The whisper reached no one, disappearing into the evening sky. Along with those words, an old memory surfaced. ——Elementary school, early grades. Got 100 on a test. So happy, wanted to show Mom right away, ran home. "That's great" wasn't what she said. "What's next?" was. Said with a smile. Not blaming. Just moving on to the next thing. That's all. But Nagisa felt like crying. The moment tears threatened to come, they pressed their lips tight. Don't cry. Crying won't change anything. Showing emotion doesn't really mean anything. That's how it's been ever since. Happy, but kept a normal face. Scared, but stayed calm. Cared about someone, but pretended not to. Never really practiced putting feelings into words. So even now, it didn't work. Nagisa didn't even understand what Karma meant to them. What is "like"? If they liked him, what then? Everything stopped before the words could come out. Another cloud drifted past. The sunset deepened slightly. --- Nagisa returned to the classroom as the sky was beginning to darken. Because the window had been left open, the classroom was a bit cold. Nagisa went to their desk to get their things——and stopped. A small piece of paper lay on the desk. Not folded, just a single memo. The handwriting was oddly meticulous for something written with a tentacle. "Starting next week, assassination training will shift to pair-based format. I will decide the pairings. ♪" Koro-sensei's handwriting. No doubt about it. That overly neat script and the heart-shaped "♪" at the end could only be written by the teacher. Nagisa froze for a moment. Pair-based. The teacher decides the pairings. Combinations began unfolding at high speed in their mind. Twenty-eight people. Fourteen pairs of two. Simple probability: one in twenty-seven. Low. Really low. The chance of being paired with Karma was basically zero. The teacher wouldn't make weird pairings. They'd decide based on rational criteria—assassination compatibility, skill balance, things like that. ——But the teacher said "7% heart rate increase" today. In that instant, Nagisa's heart jumped hard. Harder than any of the three failures on the roof. Harder than when they'd imagined Karma's profile, harder than when they'd remembered his voice. Much harder. Nagisa picked up the memo. Carefully, they folded it into quarters. Opened the desk drawer and quietly placed it deep inside. (It's fine. The teacher wouldn't make weird pairings.) They told themselves. One more time. It's fine. Definitely fine. But that face didn't look fine at all. Outside the window, the sunset spread its last red across the sky. The mountain ridgeline turned black. Soon it would be night. Tomorrow they'd climb this mountain path again. Take the teacher's class, do assassination time, and glance at the seat next to them. That was the daily life of Class E.