I finally understood the theory.
But when I turned to tell my neighbor, he was gone.
"Hey, where did he go?" I asked.
"Oh, Dr. Akira?" the assistant replied. "He's outside."
I walked out of the building.
There, leaning against a wall, was Akira.
He was smoking.
The evening wind carried the smoke into the sky.
"Bro, what are you doing?" I asked.
Akira glanced at me.
"What's with you, dummy?" he replied.
His usual angry tone.
I walked closer.
"Why are you always angry at me?"
For once, he didn't snap back immediately.
Instead, he looked away.
"You don't need to know."
His voice sounded different.
Sadder.
"What happened?" I asked quietly.
Akira flicked his cigarette to the ground and crushed it beneath his shoe.
For a few seconds, he said nothing.
Then he spoke.
"I'm always angry at you because..."
He paused.
"...you remind me of him."
"Who?"
A small smile appeared on his face.
A smile filled with memories.
"His name was Nanami."
"He was my best friend."
The way he said it made my chest feel heavy.
"But one day..."
His smile disappeared.
"What happened?" I asked.
Akira stared at the ground.
"He was in the ICU."
"I stayed with him every day."
"I thought he'd get better."
His hands clenched into fists.
"But then there was a monster attack."
The words hit me harder than any punch.
Because I knew exactly what came next.
"He died."
Silence.
For the first time, I didn't know what to say.
Akira let out a bitter laugh.
"His dream was to become a doctor."
He looked at his hands.
"So after he died..."
"I became one."
The wind blew past us.
Neither of us spoke.
"That's why I get angry at you."
He looked at me.
"You remind me of him."
For so long, my life had only been about fighting.
Training.
Getting stronger.
Surviving.
But now...
I felt something else.
Sadness.
I looked at Akira.
Tears had begun to form in his eyes.
He tried to hide them.
I stepped forward.
Then I hugged him.
For a moment, he froze.
Then he hugged me back.
I felt tears running down my own face.
"Kyoren," he whispered.
"Please..."
"Don't let anyone else die because of monsters."
I tightened my grip.
"I won't."
For the first time in a long time...
I made a promise I truly intended to keep.