Should a character be in a panel or not?
As established in the previous entry, the decision to exclude something from a comic is just as important as the decision to include something. If it helps, think of this as similar to the sound engineer’s choices while scoring the anime on whether or not a section should have music or silence.
If we have an establishing shot where a character is in the foreground and other characters are in the background, what that means is that the character who is the focal point of that panel’s composition is aware of the presence of the background characters. By that same coin, if we have a panel where “geographically speaking” a character should be in our line of sight but has been omitted, that means that this character isn’t relevant to the foreground character’s mental state. It’s also worth noting that it’s often understood that if we have an establishing shot where a character is in the foreground and other characters are in the background, the characters who are not the focal point of the composition are not aware of the presence of the characters who are the focus.
Examples:
Background characters relevant to focus character’s mental state. Focus character irrelevant to background character’s mental state.
This is a rather common means of establishing a scene in both cinema and comics. Here’s an example from a different comic:
Moving on:
Character who is logically in our line of sight omitted because they are irrelevant to focus character’s mental state.
Foreground characters relevant to focus character’s mental state. Focus character irrelevant to foreground character’s mental state.
Having established a basic foundation on when a character should be in a panel and when they should not, I also want to note that this choice can also depend on the artist’s style, but this principle generally holds in both manga and western comics. Regardless, once the artist knows a character is going to be in a scene, they should also start thinking about that character’s action. The artist also needs to think of the character as an actor on stage; the character will be delivering a performance through the artist’s drawings.