If what the little thing says is true, this plot seems a lot more like one of the movies or the OVAs. Which is by no means a bad thing (could be better with Naga though...).

I half expected Lina to start chanting the beginning of the Giga Slave and have Gourry stop her before she got too far...or maybe a bit more realistically a Ranga Blade and cleave a huge swath in the forest.

For those more familiar with the series:
Is that waitress in the OP who I'm hoping it is?