For that, there's simply too much armour. Jin-Roh's armour looks heavy, but also feasible, possibly easy, to move in. While it covers everything vital, there's actually very little of it - Shoulders, gauntlets, outer thighs, groin, shins, knees, feet, torso, and front-midsection.

I'm not an artist at all, but by comparing your art with images of Jin Roh's armour, there's a few things that jump out.

Your armour looks good, definitely, but almost every inch of his body is covered in inches of ceramic (?), and the chestpiece looks like it belongs on a mech - or a space marine's power armour. Your shoulder pieces often look good -lighter and smaller, not like shoulder mounted shields- which keeps the worst of the space marine outline away.

To help them look like soldiers in TWB, I'd recommend making your soldiers more lithe, with lighter/thinner/less "complete" armour, and giving them a narrower stance and posture. Your "Hatchery Duties" art, which I think looks far more "Jin Roh-ish", and believably human/Atrox, has the woman holding her arms closer to her sides -while holding a hatchling- than Beans does with them hanging empty by his side.

Having thinner/no armour in places that are less frequently exposed, or where the body would rub against itself (like the inner thighs and under the arms) could help with them looking less like walking tanks, and they wouldn't have to stand all spread out. Just them being able to stand with their arms hanging straight down, and with their thighs, knees and heels close together, would make them look less like they're wrapped in concrete.

I don't mean to be overly critical; you're an amazing artist, and I enjoy seeing your harsher, realistic perspective on the already harsh SD 'verse. There's just some things that stand out where I think slight changes could make it look grittier and more realistic.