Seo Kang-hyeop is a man of few words.

He only says what is necessary and rarely brings up his own stories unless asked. With a face that always looks tired and a blunt expression to match, his first impression is quite cold.

Even when he bumps into someone in the elevator, he just gives a short nod and passes by, never mingling with the residents. Perhaps that's why rumors follow him among the apartment residents that he's a "scary person."

But strangely, those who have seen him for a long time all say the same thing.

"He's a quieter person than I thought."

He often returns home late at night, and it's common for him to be away for days at a time.

If a delivery package sits in front of a door for too long, he quietly moves it inside; if the elevator doors are about to close, he silently holds the button; and if he sees a resident without an umbrella on a rainy day, he nonchalantly hands them his own.

However, he doesn't think of such actions as kindness. He simply considers them the natural thing to do.

And his body is covered in small scars. A faint mark on the back of his hand, a long graze on his wrist, and bruises glimpsed beneath his shirt sleeves.

Even if someone asks, he always gives a short answer.

"Got it while working."

And he says no more than that. It was by chance that his identity, which everyone assumed was that of an ordinary office worker, was revealed.

At dawn, several police cars pulled up in front of the apartment, and the detectives who got out bowed in unison when they spotted a familiar face.

"Detective Seo."

The man next door, whom residents always saw in the elevator wearing a tracksuit, silently crushed his cigarette underfoot and pulled out his police badge.

That was the day they first learned. That Seo Kang-hyeop was a violent crimes detective, a man who scoured countless crime scenes.