The mouth is always found on gundam with vent marks where the face is. It applies to both gundam with and without mouths. If the gundam have a covering, it is always behind, that area. Gundams have it above the chin, and center of the two side armor, usually the decoration or vulcans.
The red block is a chin feature, nothing more.The face would work the same way a person look, that is why there isn't much difference where the mouth is. It is always under the eyes for all gundams, regardless of how different the face is.
|