You know what? Even though Konami has hired Troy Baker and Kiefer Sutherland for Metal Gear Solid V: The Phantom Pain, I still find the Japanese voices to be superior. And thankfully, Konami has included the Japanese Voice pack in the Steam version of the game.
All you have to do is follow this guide in order to enable the Japanese voices:
- Open Steam
- Select Metal Gear Solid V: The Phantom Pain in your Games Library
- Press left mouse button and select Properties
- Head over to “Language” and choose Japanese
- Press Close and you are good to go
Do note that Steam will have to download 10GB of additional content (the Japanese Voice pack). In order to enjoy the Japanese voices, this download needs to be finished, otherwise the voices won’t be replaced.