Filler chapter in the manga = terrible episode in the anime.

I didn't really care for the monster of the week chapters, and this illustrates a perfect reason why some of the worthless intro chapters were cut and they sped up the introduction of Kurumu and Yukari.

I didn't have an issue with the bat this episode. Without it, Moka or dark-Moka would have to explain the specifics of why vampires are weak to water and it would look even more out of place than if the bat broke the flow of the show and explained it.