A Company Man (2012)
A Company Man is a 2012 South Korean action thriller film, starring So Ji-sub, Lee Mi-yeon, Kwak Do-Won and Kim Dong-jun. It is about a hitman who works a disguised company made up of hitmen. The story centralizing around the quiet man Mr. Ji who goes about his average killing job from day to day until he meets a single mother. Mr. Ji wanted to start a new life which then his ex-employers betrayed him by sending assassins to eliminate him.
More at Wikipedia.