Don't have a Japanese font, but in the FF's, they use Bi-suto for beast usually..and I've seen places that sell the plushie call it Slimebeth (I had no idea, I just called it Red Slime for a long time, since I had no idea what a 'besu' was supposed to be).
What other times has a DQ used 'besu' for beast? Nothing is coming to mind.