Janyeon

Yeom Joo-hwa, the boss of a criminal organization and a highly successful alpha male, hears rumors about a monster that has recently appeared in the underworld. He orders his men to take care of him, but every single one of them is defeated. Heo Moon enters the snake's den, destroys the organization, and completely overpowers Yeom Joo-hwa.

(Source: Lezhin, translated)