Doi's landlord, who considers him a troublemaker. He's been known to try to renting out Doi's house to other people during terms when Doi stays at the academy. He also doesn't know about Doi and Kirimaru's identities as ninjas, and they work hard to keep it that way.
The eponymous devil of the Devil Ring. In the past, he was the last King of the Shang Dynasty, King Zhou of Shang, Dixin.
Go is the Knight of Fire and works at a restaurant. Adopting a tough-guy technique, Go is typically the one assigning the younger members of the Leafe Knights tasks and threatening them for any misdeeds. He often uses reverse psychology as a tactic to get the younger members to do what he wants. When Himeno assumes Go's power, she can utilize the Fire Axe.