Sean Eyestone was the studio co-producer at Kojima Productions. He was also the host of the studio's official podcast, The KP Alert, and the English version of the studio's Kojima Station live stream. He replaced Ryan Payton, who left the company to join Microsoft on its Halo series. In addition, he oversaw voice acting for the series, and was one of the lead level designers of Metal Gear Solid 4: Guns of the Patriots's 4th Act (Shadow Moses). He also voiced some soldiers and extras in Metal Gear Solid V: Ground Zeroes and Metal Gear Solid V: The Phantom Pain.
According to the 5th episode of the MGS4 Integral Podcast, Eyestone is from Hawaii.
He also did commentary on the various demos for E3, Gamescom, and Tokyo Game Show relating to Metal Gear, primarily for the overseas audiences.