I don't think she's giantess...

Yeah, it's just the forced perspective. Look at the ground between her legs -- she's normal-sized, she's just very close to the viewer, who is looking at her from ground level.

You guys don't know how perspective works. There's no way she can be averaged sized.

...unless, her upper body is massively larger than her lower half.

Besides you can find cues in the soldier's shocked expressions. As well as the looming shadow that's covering most of her face/body.

heaven forbid someone's drawing follow all real laws of human proportion, perspective, and anything else

She's gon' get shot.

This seems like a perfect candidate for "What do you mean it's not Awesome" pool.

Also at pixiv #9634371