Free-willed Gear from Guilty Gear who was originally a human child and changed into the way they are today by the Post-War Administration Bureau.
In Guilty Gear, they plotted to revive Justice. In Guilty Gear X, they dedicated themselves to protecting Dizzy. They were adopted by Kliff Undersn.
They fight using a scythe made of blood along with their unnatural Gear powers.
Testament is non-binary according to their official bio as of Guilty Gear Strive, with prior depictions leaning masculine.
They have succubus familiars at their command.