
Quick answer — Sho Sudou voices Yamaguchi in Rozen Maiden: Zurückspulen, Chihiro Ukawa in Grisaia: Phantom Trigger THE ANIMATION.
Sho Sudou voices Yamaguchi (Rozen Maiden: Zurückspulen), Chihiro Ukawa (Grisaia: Phantom Trigger THE ANIMATION).
Yamaguchi is voiced in Japanese by Sho Sudou.