They literally changed the intro just to give it a little more characterization. This anime is so underrated. This is the OVA/Extra episode they threw in and I thought it was great. The editors and writers obviously a lot put time into this. The purpose of this was give you a laugh with the same elements presented in the show. It's way more light-hearted and its supposed to be taken seriously. The art style was on par with the rest of the show. There was more focus on Kirie and it almost breaks the 4th wall. It's episodes like this that made me wish the serieswas longer or had more time to fully develop all of the characters.

I would for sure watch this once you are done with the original series as it is light hearted.