This is a missable achievement during chapter 13.
This is a guide from psnprofiles.
During Chapter 13, you'll have a highway shootout in a vehicle. The yakuza who you need to shoot for this achievement comes at about halfway through the sequence. He's easily distinguishable from the other yakuza since he's wearing a white suit and has an afro. Make sure you have some of Kiryu's Heat Eye available as he can be tricky to hit otherwise. This ability recharges over time. When you see him get close, hold LB to activate it and slow down the action. He doesn't take many shots to go down, just make sure he doesn't escape. You can check the video below for his exact location.