Soft Night

In a quiet rural village, there's a place where laughter never seems to stop. From children running around to white-haired elders sitting nearby.
There, is a small piano academy run by the village’s young chief.
For reasons no one really knows about, a hollow-eyed man the chief refers to as his spouse, teaches every single student on his own. A one-man operation, day after day.
But beneath this seemingly peaceful routine lies a far more dangerous truth...
Once the academy closes its doors and night settles in, the chief and the instructor begin pulling out various murder weapons, one by one, from a secret storage room hidden inside the academy.
A former crime syndicate boss who abandoned his organization, and the undercover police officer assigned to surveil him.
A truth the villagers know nothing about.

(Source: Bomtoon, edited)