Imbecile (1985)

They're a five-member girl group, Thriller. They might have chosen different paths in life but when it comes to music, they share the same ideals, led by their manager Seok. Taking after his policeman father, Seok is a man's man, helping the girls through their failures and sharing their happiness in success. He's a righteous, strong man ready to protect them whenever they fall in danger. And, sure enough, danger comes! Driven away by their conflicts and different personalities, the girls find themselves in trouble, one of them becoming a victim of rape. But fear not, Seok will try to get every single one of those responsible for such a crime. And when Seok gets angry, he becomes a Crazy Boy.