Sometimes all it takes is a simple and subtle gesture to express a wide range of emotions. For example, the motion of putting one’s hand on their neck is said to indicate anxiety or agitation. You’ll also commonly see characters in anime or manga gently rubbing the backs of their necks when flustered or embarrassed.
Hajime Saito (from the Hakuouki series) looks like he has many things on his mind as he rests his arm upon his neck.
Have a look at the artwork below and see what sort of feelings arise for you