Trenia is a mysterious girl who turns out to be the physical form of the Sacred Tome in Makai Kingdom. Originally appearing to be a normal girl walking around aimlessly, Trenia's presence in the Netherworld is a mystery to everyone, since only Overlords can exist there. It is later revealed that she has the ability to see the future and is actually the Sacred Tome's soul that was pushed out when Zetta bound himself to the book.
Trenia loves to tease the other Overlords and always retains a carefree and ditzy attitude. She has a tendency to wander off or run after butterflies mid conversation due to her ability to finally walk around and enjoy herself, doing things she couldn't do as a book.