>>23310371
>>23310377
>>23310379
Short answer is antigravity tech.

Long answer is the entire thing is skeletonized to save as much weight as possible, it's got a second pair of arms and legs meant specifically to brace the thing, it can only fire while stationary, half the barrel is a complex system of vents to mitigate recoil by redirecting the exhaust gases, and it needs pretty much a full squadron to babysit it while it does its thing. It's noted in-universe to be gross overkill and completely impractical, only made as a vanity project by the most vain of engineers, Amaterasu, who is also Emperor of the Galaxy and/or God.

Oh also the only kills it gets are using its sword, and it has laser eyes but Amaterasu is a retard so they burn out the eye sensors when they fire