Nyctodon

Nyctodon, meaning "Night tooth", is a smaller offshoot of the fearsome monster Guirodon. Nyctodon don't fly as much as Guirodon, preferring to chase their prey on the ground. True to their name, they hunt in darkness.
Nyctodon have bright markings that glow as a warning, telling opponents and predators that their body is full to the brim with a corrosive acid. They can shoot this acid from their beaks with astonishing accuracy, hitting their prey to start predigestion.
Also unlike Guirodon, Nyctodon does not become useless if its tail is removed. Its biggest weakness is its thin wing membranes, which are much weaker than those of its flying counterpart. However, it can still run even if they are damaged, so the best course of action when fighting is to behead it quickly.

Nyctodon are exceptionally intelligent and have been reported learning sapient language, which makes the subject of hunting them a controversial and ethically ambiguous topic. Some Nyctodon, thanks to headmaster Sceri, have been completely reformed and now live as "normal" of a life as they can. No cure for their condition has been found, but they are accepted as people once they undergo reformation.