A Modern Warfare 4 role for Reiner Yang is unconfirmed. There is no established character-and-actor pairing to give under that exact name. Treat it as an unresolved name, rather than a confirmed member of the campaign cast.
Confirmed names to distinguish
If you are trying to identify the young South Korean soldier at the center of the campaign, the character is Private Park Hyun-Jun, played by Young Mazino. Lieutenant Ko Jin-Hyuk is played by Lanny Joon. Neither pairing establishes Reiner Yang as an alternate character name, performer name, or translation.
Private Park Hyun-Jun is played by Young Mazino. This image does not depict Reiner Yang.
Other confirmed pairings include Barry Sloane as Captain John Price, Samuel Roukin as Simon “Ghost” Riley, Prisca Kim as Ri Ju-Young, and Mads Mikkelsen as The Archer. These names help identify the established cast; they do not identify a person called Reiner Yang.
What remains unknown
No character identity, performance credit, biography, or connection to another cast member can currently be assigned to this name with confidence. A similarly named social profile, professional listing, or unrelated news result is not enough to establish that connection.
If the name appeared in a clip, image, or discussion, check its exact spelling and whether it refers to a character or an actor. Keep the original context when checking the credits. Until a clear credit connects the name to the game, there is no supported role description or personal history to add.
Game credit and casting references: Cast and List of Voice Actors – Call of Duty Modern Warfare 4 (MW4)｜Game8, Call of Duty Modern Warfare 4 Cast Explained: Mads Mikkelsen.
Related reading
Continue with Cast & Voice Actors, Young Mazino as Park, and Lanny Joon as Ko Jin-Hyuk.