The Majuu (Demon Beast) race.
On nights of the full moon, the Gabranth blood strengthens. Not all Majuus run wild. Matured [Majuus] have a full understanding of their bodies, thus being capable of controlling their blood.
There are fellows who don’t lose to either blood line, to the point that they can control it completely.
That’s right, the characteristic of a Majuu, is that they inherited the physical characteristic from both race, but they didn’t inherit the unique skill from them. Which is Magic and Binding. Since the blood cancel each other, they can’t be used.
Of course, cross-breeding is against the law. If the child is found, it will either get banished or eliminated.