Calamity (Or CAMILIA if you're referring to the AI) Is a specialized test bed prototype of a Leopard 2A7+ made by Germania that surpassed everyone's expectations, it was only intended to be a weapons test platform for both the highly classified RTN masking coat, a powerful railgun & an AI that fully made it autonomous.
But on January ████, ████ at ███████ ██████████, something unexpected happened, as the AI became sentient after it was introduced to an unknown crystal power reactor to which it started to roam around aimlessly.
From that point on the sentient AI was unusually cooperative especially to it's own creator, even if it had a mind of it's own it still seemed to follow orders despite not placing any malice suppressing code into it's system.
Sooooo yeh it's basically a custom tank that I made, meow.