| Spoiler warning!|
This article contains plot details and spoilers for a current or future season.
|“The Oni are said to be all powerful beings, demon that predate Ninjago.”|
|— Zane, The Mask of Deception|
The Oni were a race of demons, mentioned in Season 8. They were the first evil to ever come into existence, as well as the creators of the three powerful Oni Masks. They inhabited the Realm of Oni and Dragons, the first realm in existence. It is unknown if they are still alive by the time of Season 9.
Before the existence of any other realms, there was the Realm of the Oni and the Dragon. In this realm existed two races; the Oni and the Dragons. The Dragons had the power to create, while the Oni had the power to destroy, and so they waged a never ending war on each other. One day, however, a child was born, having both the powers of Destruction and Creation. When the Oni and the Dragons fought over which side the child should choose, the child left their world to start a new one, called "Ninjago."
Soon afterwards however, some of the Oni pursued the child to his new realm of existence, creating a temple deep within Primeval's Eye, where they depicted their origins on the walls of the temple. They would also seal away the Oni Mask of Hatred within the temple, which could only be taken by a being with Oni blood.
- First Spinjitzu Master (of Dragon descent)
- The Oni are based on Japanese folklore.
- The Oni were the first evil to exist in the realms.