"Why are you so mean to me?"
Because, Suzune, you have a visible bust. If you were flat and/or a loli, you wouldn't be receiving this irrationally intense and consistent antipathy.
Seventeen chapters in, and Mr. J-pop MC is only becoming more and more hostile toward Suzune (generally; rarely does he throw her a bone). This tsukkomi business is one thing, but it's jarring when compared with how he's so very kind and friendly to just about everyone else:
-Amako is a little girl, which apparently makes
many mangaka quiver in excitement. Usato has no reason to treat her harshly, but you can bet he'd never do so anyway;
-The enemy-turned-Rose-victim Felum is someone who opposed him on the battlefield; I don't remember Suzune's wound, but Kazuki was skewered by Felum in her armor. Felum very nearly killed both of them--and he's as gentle and amiable as can be with her.
-Speaking of combat, Usato very foolishly healed an enemy combatant in the process of extracting a wounded ally. I suppose he thought that'd bring about a change of heart? Maybe that enemy would throw down his weapon as opposed to--I don't know--using his second wind to continue fighting with lethal intent against Usato's allies?
But Suzune, for all her endearing weirdness, receives something that's going beyond the usual tsukkomi/unpleasant behavior usually reserved for girls bustier than she is: it's as if he automatically chooses disdain for anything she says, including things that are
obviously indicative of romantic interest (he's reached that point in this chapter). The author seems to be struggling with his character design orders, the ones most mangaka seem hellbent on following: he couldn't make Suzune too busty (the author knows what a busty woman looks like--proven with the shorthaired enemy commander), as she's the female lead; neither could he make her flat or a loli, because he can't let Usato give her the donkan treatment if he does. So Suzune is caught in between: small enough to be flattened for the anime, but sizable enough to be given
a bust increase for promotional material in magazines to be sold. And that just doesn't make things easy for Mangaka-kun.
I'm still catching up, but I'm calling it now: he's eventually going to blow up at Suzune, and there'll be as valid a reason for it as for his healing enemies on the battlefield.