The Orochi has a slender build, which can be considered serpentine to a certain extent. It has a round head, and three eyes, with one slitted on the forehead. In the original Orochi, it served no purpose.
The Orochi was armed with a Blaze Luminous system that was bright red.
The Orochi's main weapon was a single katana. The katana was shown to be capable of cutting through anything, using a high frequency vibration system.
The Orochi's final weapon was the RESIR blaster. It fired a violet beam, that was designed to burn through a Knightmare, then explode.
The Orochi was first brought to life when Lelouch used it in the run down part of the Pendragon Settlement. It made short work of the opposing Knightmares, and would have finished the job, had Lelouch not have been called off.
It would serve as Lelouch's primary weapon, until it was replaced in the second arc by the Orochi Kira, which was upgraded with flight units. The Orochi Kira would late be heavily damaged by Shirley's Andarta Vanir.
However, the original Orochi was actually being upgraded, and Lelouch would reveal the Yamata no Orochi to the people. It would be responsible for the defeat of the other Kaminoryuu.
It took place in the final battle, in which it managed to defeat the Andarta Vanir. However, Lelouch would later destroy it himself, but stabbing the Orochi in the stomach with its own sword.