"At this length, it indicates I want to kill someone. So, Principal... do you find this evidence persuasive enough?"
Kira Nanami spoke with a chilling, flat serenity.
"I believe you, I believe you... Kira-kun, please, put your hand down first..."
Perhaps because the evidence was so visceral and undeniable, Principal Gakuganji nodded with uncharacteristic obedience.
Kira, ever the reasonable man, returned his right hand to his lap.
He reached into his inner coat pocket with his left hand, producing a clean square of cloth which he laid perfectly flat on the floor. Then, he pulled out a pair of high-quality, precision nail clippers.
Snap.Snap.Snap.
The crisp sound echoed against the walls of the quiet room. This sound always brought Kira a sense of tranquility, akin to floating in the center of a vast, azure ocean while the gentle murmur of waves flowed past his ears.
As he trimmed, he continued the conversation:
"We've caught it early; the curse hasn't reached its final stage. Before my... the enemy's next terrorist attack, we must locate the 'Ground Zero' of the infection."
What he actually meant was: Before I have to clock out.
"Kira-kun, that is a monumental task. Kyoto is vast. Finding the origin point is like searching for a needle in a haystack. How about I dispatch half the school's sorcerers to assist your search?"
Kira gave Gakuganji a meaningful look and shook his head. "That won't be necessary."
He patted his hands, ensuring every clipping fell onto the cloth before carefully funneling them into a glass jar. Only after this ritual was complete did he exhale a sigh of relief, wiping non-existent sweat from his brow before standing up.
"I have a fairly good idea of where the curse was planted."
"Oh?"
Gakuganji's eyebrow twitched again, but he masked his shock well, asking kindly, "And where would that be?"
Kira pulled a rolled-up map from his breast pocket, smoothing it onto the low table. He took a marker and began to sketch coordinates.
"Our current data is as follows: An unknown curse, planted roughly two weeks ago."
"Yes, go on."
"It spreads through negative energy and features human-to-human transmission."
"Therefore, it is simple. We treat it like a virus. The area with the most severe symptoms is the point of origin. Where are people the most desperate? Where is the morale at its lowest?"
"That just turns a haystack into a lake," Gakuganji countered. "Are we to send sorcerers door-to-door with surveys? 'Excuse me, are you happy? Is your marriage fulfilling? Is your child actually yours?' We can't investigate like that."
Kira nodded in agreement. "With that alone, you are correct. It would be impossible."
"But it has another characteristic: its Cursed Energy fluctuation is so faint it goes undetected. Even sorcerers like us were snared without realizing it."
"Kira-kun, I apologize for my earlier skepticism—please, stop the suspense."
"...The symptoms vary by individual. I hypothesize the severity is linked to the victim's Cursed Energy grade," Kira said, satisfied.
Gakuganji straightened his back, listening intently.
"Your student, Mai Zenin, is clashing with Momo Nishimiya. They are Grade 3. Miwa Kasumi is extremely irritable; she is semi-Grade 2. You and I are Grade 1 equivalents, and we are occasionally losing control of our tempers...
As for the civilians? I've seen a man butchered out of pure spite. I've seen a neighbor plant 'mouldy money' at a friend's door. I've seen the rising suicide rate. It is clear: the curse has a more profound effect on those with little to no Cursed Energy."
"I see. So, Cursed Energy acts as a form of biological resistance. The virus is the same, but the 'immunity' differs."
"Precisely. This gives us two traits: Transmissibility and Resistance. But if we use the virus analogy, there is a third property."
Kira set the pen down, looking Gakuganji in the eye.
"Proximity."
"The closer you are to the source, the higher the viral load, and the easier it is to be infected. It is easily proven: you and I have high Cursed Energy—high resistance—yet we are both showing symptoms. Meanwhile, civilians in the Ukyo Ward seem relatively unaffected; their suicide rate isn't nearly as high. There is only one conclusion: our current locations are closer to the source than Ukyo is."
"So, we can build a transmission model."
Kira dripped a drop of black ink into the center of a teacup. The ink stained the center dark before slowly bleeding outward. The center remained a pitch-black dot, while the edges faded into a pale grey that blended with the green tea.
"The darker the ink, the higher the infection rate. It radiates from the center in a perfect circle." He pointed to the faint grey edge near the rim. "This is Ukyo Ward."
"And then?" Gakuganji's expression was grim, his fingers tapping the table. "We still don't have a coordinate."
"Our Cursed Energy levels are comparable, and our level of infection is identical," Kira replied.
The only difference is that your loss of control leads to flipping tables, while mine leads to murder. In Kira's mind, a human was no more precious than a table. They were both just objects in his environment. Therefore, their "symptom levels" were equal.
"Curses are not exactly like biological viruses. Viruses have variables. Curses are singular, rigid, and follow strict logical laws."
This was why Kira had chosen this profession; he loved things that followed rules.
"If our 'Resistance' is equal and our 'Infection' is equal, then according to the law of proximity, our distance from the source must also be equal. Down to the millimeter."
Kira used the pen to dot a dark region on the map. "This is my apartment."
He moved to the other side of the circle, measured the distance with his eyes, and placed another dot. "This is the school."
"You've studied middle school geometry, I assume?"
He drew a line connecting the two points, then drew a second line—a perpendicular bisector—cutting through the center of the first.
"The source of the curse lies on this line."
"We can estimate Cursed Energy levels, but 'Infection' is psychological. How can you be so sure our levels are the same?"
"I studied criminal psychology for several years, and I've read the law. Based on my observations of your outburst just now, I can say with professional certainty that your anxiety level is a perfect match for mine."
Kira spoke without looking up. Why the hell is a sorcerer studying criminal psychology and law? Gakuganji wondered, rubbing his temples.
"Even if there is a slight margin of error, it is within tolerance."
Kira checked his watch. He began circling areas on the map. "Applying the model to the geography... here is the school... here is my home... connect them... bisect them."
He set the pen down, pointing at the black line on the map. "The location is here. Or very close to it."
He erased more than half the line—the sections closer to Ukyo Ward, where the infection was lighter.
"Once we filter for uninhabited areas, we will find the source immediately."
"...I'll arrange an investigation at once." Gakuganji nodded sharply, his face full of genuine admiration. "Kira-kun, we are lucky to have you. Truly, the most unique sorcerer of our time."
Hmph. Performance artist, Kira thought. Aloud, he simply gave a humble smile. "You flatter me."
As he had thought from the start: a pointless conversation. He just wanted to go home.
The summer weather was fickle. Moments ago, it was radiant; now, clouds were piling layer upon layer, pressing against the darkened horizon.
As a bolt of silver lightning tore through the sky, the reservoir of the heavens broke. Rain began to hammer down on the budding wheat fields.
It's raining. Good thing I brought an umbrella.
Under the black canopy of his umbrella, Kira tilted the handle, clearing his line of sight. Before him stood a row of sorcerers dressed in black. They stood in the downpour, hoods up, the silver buckles on their boots glinting in the gloom.
"Let's go."
Kira turned. His boots stepped into a puddle, sending out ripples that were immediately crushed by the synchronized march of the black boots behind him.
Watching the sun vanish behind the thunderheads, Kira thought:
Let's move. We finish this before five.