Robo-Samurai

The Robo-Samurai is a giant samurai robot.

Biography
After failing to defeat a giant robot, Jack finds himself in an underground sewer, surrounded by peaceful human-sized robots. Jack is told by a robot that their city was under attack by something they created, called Mondo-Bot, and that they built their city over a magical city of giants. Believing Jack to be the key to awakening one of the giants, the robots hand him a breathing apparatus and send him into the sunken city of giants to find one. Jack finds a giant stone samurai, who absorbs him into itself and comes alive. In an intense battle, the Giant destroys Mondo-Bot and returns to the sea, releasing Jack.

The Giant is later commandeered by the robot inhabitants of Andromeda, who came to the aid of Jack with his allies. It fought against Aku, managing to briefly give Aku a beating and damage him. When Aku rained a hailstorm upon the allied army, the robot endured the assault, however its occupants and pilots were killed.

It is unknown how Aku's destruction in the past affected its existence, not to mention the robots of Andromeda's as well.

Abilities and traits
In comparison to the Mondo Bot and the inhabitants of Andromeda, the Robo-Samurai appears to be mystical in nature, being made of stone and absorbing Jack into itself with beams of energy from its eyes. It is highly resilient to conventional weaponry and laser fire, suffering minor external damage during Mondo-bot's initial assault and being unharmed by the explosion of its backfiring cannon.

The Robo-Samurai's primary weapon is a large katana, but it also exhibits proficiency in hand-to-hand combat. It likely has all of Jack's skills, but its sheer size makes it less effective at combat than its pilot. However, its opponent is similarly hindered by its own size, allowing Jack to use his martial arts to their full potential against it.

Trivia

 * The Giant conceptually resembles God Mazinger, another stone giant powered by a human. It draws Jack into itself the same way God Mazinger draws its "pilot" into itself. Both operate similar to giant robots without actually being robotic in nature.
 * The exact nature of the Robo-Samurai and its fellow giants is never elaborated upon, other than they are mystical in nature and seemingly sentient, as their city is what the robots of Andromeda built over.
 * It is implied that is capable of minimally harming Aku as he lets out an indication of pain as The Robo Samurai tears his horns off.