The City of Violence

After an ex-gangster named Wang Jae is terminateed by a gang of punks, his four childhood friends come back together for the first time in nearly twenty years. Each of them has gone different ways, Tae Soo a detective, Pil Ho a powerful mobster who once worked with Wang Jae, Seok Hwan a reformed mobster and his brother Dong Hwan a math teacher. They reminisce about times gone, their mischievous teen years,and a pact they made on a school picnic.
(Source: Wikipedia)