A common solid-ammo pistol caliber originally made by Ketsurui Zaibatsu and used throughout the Democratic Imperium of Nepleslia and Yamatai star empires. Shorthand is “10 mm KZ”. It is the Star Army of Yamatai's only official solid-ammo pistol cartridge, while the Red Star Army of Kennewes use it as a primary cartridge, the secondary being the .45-caliber Zen Armaments.
The 10 x 25 mm KZ is also manufactured by Zen Armaments.
In-character use of this cartridge is hard to find due to the prevalence of energy weapons. However, it is generally accepted the cartridge is potent, possessing excellent stopping power and and penetration, depending on the type of rounds used. Nekovalkyrja, being slightly stronger than the average human, are able to handle the cartridge's presumed recoil better than most. Yamatai's Type 28 General Service Pistol uses a rotating barrel to help compensate for recoil.
The 10 mm KZ is essentially a SARP version of the infamous 10 mm Auto, a cartridge originally designed for the infamous Bren-Ten pistol. The cartridge has seen some resurgence in popularity in recent years by pistoleers looking for a powerful, long-range cartridge, but for the most part it has been eclipsed by the .40-caliber Smith&Wesson due to the cartridge's recoil in nearly every pistol chambered for it.