In YGGDRASIL, Grenbera Devil Leeches were one of the monsters that spawned around the swamp area where the Great Tomb of Nazarick was located originally. It guards the unconquered Great Tomb of Nazarick from enemy players and NPCs if caught on sight trying to trespass into their territorial ground before reaching the tomb.
Since they are leeches, this can suggests that they have the form of predatory or parasitic worms.
Grenbera Devil Leeches are monsters that have adapted to living in a swamp-like environment. In YGGDRASIL, their level can reach as high as level 64.
- The members of Ainz Ooal Gown avoided confronting this monster as they made their way to Nazarick.