The Edge of Equilibrium

Chapter 3: System Failure

It took two weeks, but the case finally broke open.

Masato dropped a folder of traffic camera photos onto Reiji's desk. Beside him, Mio had her small notebook ready. Reiji let out an irritated grunt, shooting Masato a look for interrupting his typing. Still, he opened the folder.

"Your instinct about gas dynamics turned out to be right, Professor," Masato began, loosening a tie that felt like it was choking him. "We traced the suspect through traffic cameras on the road behind the building. One of the victim's seniors at the faculty was caught on camera in the alley right below his lab window, the night it happened."

Reiji picked up the low-resolution photo. His eyes moved over the image, a man in a dark raincoat, standing near an outdoor AC compressor unit.

"He fed it in from outside," Reiji murmured, setting the photo down. He turned to the whiteboard, grabbed a marker, and sketched out a rough diagram. "Older lab cooling systems usually have a fresh-air intake from outside. With an extremely thin, flexible silicone capillary tube, he could have run it through the ventilation gap without damaging the window seal."

Mio scribbled quickly. "But how did the concentration get high enough to kill him?"

"Laminar flow," Reiji answered calmly, glancing at the junior detective. "Pure carbon monoxide, fed slowly through a small tube, straight into a sealed room. It would only take him under two hours to push the concentration up to around 3,000 parts per million. Asleep, the victim would never have woken up."

"And guess who's the only one at the faculty who knew the victim's overnight schedule?" Masato cut in, leaning his hip against Reiji's desk. "His own senior. The same man who'd told him to stay overnight to keep the incubator running for their research samples."

With that, the case was practically closed. All that was left to fill in was motive: thesis plagiarism, academic jealousy.

Mio looked at Masato, eyes shining. "You were amazing, Senior. If you hadn't pushed forensics to recheck that cherry-red discoloration, this would've already been closed as a natural death."

"That's the professor's logic at work, not mine," Masato deflected easily. "I just had a hunch. I never know why these things work, that's why I keep coming back to hash it out with him."

Mio shook her head. She stepped over, picked up Masato's jacket where he'd tossed it over the back of a chair, and smoothed the collar. "Still, you're the one who kept pushing until we got here. You worked really hard on this one."

Masato just laughed quietly and let his junior fuss over his coat.

Across the room, Reiji had gone back to the thermodynamic equations on his whiteboard. He suddenly stopped.

He stood frozen. His eyes stayed fixed on the rows of numbers and variables in front of him, but his mind refused to process a single one of the symbols. Behind him, Masato's warm laughter and Mio's soft smile felt like an interference wave, corrupting the frequency of his thoughts.

His chest tightened. His heart beat at an inefficient rhythm. He looked for a biological explanation; maybe the oxygen level in the lab had dropped. But when he turned and saw how few inches separated Masato's shoulder from Mio's, something told him oxygen wasn't the problem.

His logic took over, landing on a conclusion that was entirely wrong, though to him, it felt like the only reasonable one. After a full week of watching them, it seemed obvious: Masato and Mio were building something. And his own presence, all this talk of physics, was nothing but an obstacle standing in their way.

"Masato," Reiji said. His voice came out colder, flatter than usual.

The detective turned. "Yeah?"

Reiji set his marker in the tray. He kept his eyes on the stack of folders instead of on his friend's face. "This case is closed. For whatever comes next, or if there are files to hand over, you don't need to bother coming here anymore."

The room went silent. Mio blinked, confused, while Masato's hand froze midway to his coffee can.

"What do you mean?" Masato asked quietly, the smile draining slowly from his face.

"Have Mio come alone from now on," Reiji went on, his voice flat, drained of feeling. "She's the one who's always taken the notes and put together the detailed reports anyway. And you'll have your hands full writing up the case. Both of you coming here serves no purpose. Let her handle the data."

A long silence stretched out. Masato looked at the bespectacled man in front of him with an expression hard to place. A sharp pain cut through his chest, even though he couldn't have said why.

To Masato, the meaning seemed obvious. The professor, a man who'd never once shown interest in worldly things, let alone romance, had suddenly, specifically, asked for a beautiful young woman to come visit him alone.

A crooked smile, cynical and edged with bitterness, finally settled on the detective's mouth.

"I see," Masato said, his voice dropping low, cutting through the cold laboratory air. He glanced toward Mio, the movement stiff. "Didn't know the genius professor had finally found an interest in something other than physics formulas. Good choice, Professor."

Reiji flinched, barely more than a blink. "Masato, that's not—"

"Let's go, Aizawa. Back to headquarters. We shouldn't waste any more of the Professor's precious time," Masato cut him off sharply. He turned without waiting for an answer, walking toward the sliding door with heavy steps. Mio, clearly confused but following anyway, headed out after him, carrying his jacket.

Reiji opened his mouth. He wanted to say the name. He wanted to explain that Masato's whole hypothesis was wrong. But his vocal cords refused to work. What was he even supposed to say? That he'd sent Masato away precisely because he couldn't stand watching him laugh with someone else?

He couldn't make his own logic form the words. The fact was too absurd, too far from anything scientific, for a man like Reiji Kanzaki to say out loud.

Only once the sliding door clicked shut, leaving Physics Laboratory No. 13 completely empty, could he move again. Even then, all he could do was stand there. For the first time in his life, he felt truly foolish.