The early morning at Sobu High School was as mundane as ever.
The classroom of Class 2-F was filled with the subtle scent of chalk dust, old textbooks, and adolescence. Standing at the podium, Shizuka Hiratsuka announced in her slightly smoky voice, "We have a transfer student today."
In a back seat by the window, Hachiman Hikigaya was trying his best to compress his presence down to zero. A transfer student? Hah, just another poor soul destined to be assimilated into this school's boring daily routine. He glanced out the window; the cherry blossoms hadn't all fallen yet, and the sunlight was a bit too bright.
The classroom door was pulled open.
First, a pair of polished black leather shoes stepped in, followed by a well-tailored dark school uniform, and finally—
"I am Amon."
The transfer student stood by the podium, smiling. His smile was just right, neither exaggerated nor shy, as if its curvature had been meticulously calculated.
Most striking was the monocle over his right eye, with a fine silver chain dangling by his cheek, swaying gently as he tilted his head.
"My hobby is observing humans," Amon continued, his voice gentle and clear. "My specialty is... creating a little bit of 'error.'"
When he said the word "error," the tip of his tongue lightly pressed against the roof of his mouth, as if savoring a dessert.
The classroom fell silent for a moment.
Then whispers broke out—"A monocle?" "So retro..." "What kind of specialty is 'creating errors'?"
Shizuka Hiratsuka cleared her throat. "Amon-san previously studied abroad. Now, your seat—" She scanned the classroom, her gaze landing on the empty desk by the window, where cherry blossom petals still lay.
"There," she said, pointing. "The empty spot next to Hikigaya."
Hikigaya's eye twitched. It was over. His "Fortress of Solitude" was about to fall.
Amon walked toward the seat, his pace as composed as if he were inspecting his own territory. He sat down beside Hikigaya, turned, and smiled.
"Please look after me, desk-mate-kun."
"...Hachiman Hikigaya," Hikigaya muttered, staring at the wood grain of the desk. This guy's smile gave him an instinctive bad feeling—it was too perfect, so perfect it felt like a mask.
"Hikigaya-kun," Amon repeated smoothly, then turned toward the window. "The cherry blossoms are beautiful. But isn't it a bit improper for petals to fall on a desk? A perfect spring, a perfect campus, a perfect desk—yet a petal destined to wither has fallen upon it."
Hikigaya didn't respond. This guy had a strange way of talking.
---
First period was math. While the teacher derived formulas on the blackboard, Amon listened with his chin resting on his hand, occasionally jotting things down in his notebook. But Hikigaya caught a glimpse and saw that what was written wasn't math formulas at all, but scattered observations:
"Subject A: Girl in the front row. Flipped her hair three times in ten minutes; frequency is stable."
"Subject B: Boy in the back-right. Glanced at his phone seven times, each lasting about 3.2 seconds."
"Subject C: Teacher. Excessive repetition of adjusting glasses; possible compulsive behavior."
...What is this guy doing?
---
When the bell rang, Amon closed his notebook and turned to Hikigaya.
"Hikigaya-kun, I heard this school has a very interesting club."
"...Which one?"
"The Service Club," Amon said, a glint flashing across his monocle. "I heard there's a president there who pursues 'absolute correctness.' I'd really like to meet her."
Hikigaya's alertness instantly spiked. Service Club? Yukinoshita? What does this guy want?
"You're going there?" Hikigaya asked cautiously.
"Yes. After all, to observe humans, one must start where the observational value is highest." Amon stood up and straightened his collar. "By the way, Hikigaya-kun, you belong to the Service Club too, don't you? Why don't you lead the way?"
It wasn't a question—it was a statement.
Hikigaya sighed. He knew his peaceful days were over.
---
The door to the Service Club was slightly ajar.
Yukinoshita Yukino sat by the window with a document spread out before her. Sunlight streamed through the glass, casting a pale golden sheen on her long black hair. She was speaking to Yui Yuigahama:
"According to the Student Council's request, the dispute between Yamada and Sato from Class 2-C is essentially a misunderstanding caused by poor communication. I have developed a mediation plan: first, have both parties engage in structured dialogue with a third party present; second, clarify the boundaries of their respective demands; and finally, reach a written agreement to prevent future conflicts."
Her voice was clear and calm, each word like a precisely polished component.
Yui Yuigahama listened attentively and nodded. "Yukinon, you're amazing! You've thought of everything!"
"It's just basic analysis and countermeasures," Yukinoshita said flatly. "As long as the correct steps are followed, most interpersonal problems can be properly resolved."
"Provided that the 'correct steps' can actually be followed."
The door was pushed open.
Amon stood there, smiling. Hikigaya followed behind him with an "I want no part in this" expression.
Yukinoshita's gaze shifted to Amon—more precisely, to the monocle over his right eye. She frowned slightly. "And you are?"
"The new transfer student, Amon." He walked in as naturally as if he belonged there. "I heard problems can be solved here, so I came to observe. After all, Yukinoshita-san's 'correct problem-solving method' is quite famous."
Yukinoshita studied him for a few seconds. "The Service Club accepts requests, but we do not provide observation services. If you have no legitimate business, please leave."
"Legitimate business..." Amon lightly tapped the back of a chair. "I heard you're handling a mediation. Coincidentally, I'm very interested in how humans resolve conflicts. May I observe? I promise to remain quiet."
His tone was sincere, his smile harmless.
Yukinoshita hesitated. Turning away a transfer student who wanted to "learn" conflicted with her principles.
"...Fine," she said at last. "But do not interfere."
"Of course."
---
Amon listened as Yukinoshita outlined her plan in meticulous detail. Every step was precise, every contingency accounted for.
When she finished, he smiled and clapped lightly.
"A perfect plan."
Everyone looked at him.
"Clear logic, complete steps, all variables considered. Truly admirable."
Yukinoshita narrowed her eyes. "And?"
"And so..." Amon walked to the window. "It is destined to fail."
Silence.
"What do you mean?" Yukinoshita asked coldly.
"Your plan is too perfect. Reality cannot sustain perfection. It always introduces a small 'error'—a trivial variable—that disrupts everything."
"Are you questioning my plan?"
"Not questioning. Stating a fact." He bowed slightly. "Let's wait and see."
---
And reality… did exactly that.
A stomachache. A missed student. A delayed notice. A sudden illness. A scheduling conflict. Rain.
Each insignificant.
Together—fatal.
---
Under the drizzle, Yukinoshita stood still, umbrella in hand.
"It's been postponed," she said calmly, though her grip tightened.
Amon passed by with a black umbrella, untouched by the rain.
"See? Told you so."
He leaned slightly closer.
"Reality loves inserting small 'errors' into perfect plans."
His smile softened.
"You pursue absolute correctness. I enjoy inevitable errors."
He walked away.
---
Hikigaya watched his back.
"...Yeah," he muttered. "Trouble has definitely arrived."
Outside, rain slid down the window. A cherry blossom petal clung to the glass, then slowly drifted downward. Like a perfect period, smudged by water.