The Iron Oni is an ancient robot suit turned almost living weapon of destruction. It first appreared in the Sonic Universe comic series published by Archie Comics.
It is a giant robotic battle suit built with ancient technology in a lost feudal era within planet Mobius' recorded history. Covered in a tough green armor that resembles a samurai with an Oni-like face. On it's chest is now a gold and emerald-green emblem of the Iron Dominion branded by the power of the Iron King's former wife, the Iron Queen, who animated it with her dark magic and sought to use it as the ultimate weapon in the name of her diabolical kingdom.
After he escaped from his uncle's clutches, Snively went to the Dragon Kingdom and found the robotic suit known as the Iron Oni.
When Doctor Eggman, as well as his lackeys Orbot and Cubot, had finally found Snively with his love, the Iron Queen, he challenged him to fight him.
Ultimately, Snively had lost to his uncle when the Iron Oni was destroyed in battle against Dr. Eggman's robotic creation, the Egg Beater.
Trivia
- The Iron Oni is likely based on the Oni, demonic monsters in Japanese folklore.