|1st appearance:||I Know Why the Caged Bird Kills|
The Oniis a Japanese demon that followed Dr. Venture home after his trip to Japan. The only people who were able to see it were Dr. Venture, Dr. Orpheus, and its apparent master, Dr. Henry Killinger. The demon tied itself to Rusty with an invisible string so the two could not be separated. Rusty foolishly locked the Oni in the trunk of his car, causing it to take control of the car and drag him around. Rusty and Dr. O decided to get in the car and let the demon drive them to wherever it wanted to take them, hopefully explaining its presence. The Oni brought them to an old run down Motel run by Myra Brandish, Rusty's former bodyguard and insane stalker. The demon turned out to be under the direction of Dr. Henry Killinger, who had hopes of reuniting Rusty and Myra.