The first OVA is very good, a solid 7, or you can stretch it to 8. A very cute style, decent animation, not too banal for this kind of story, the main character is a militant lesbian, plus there are perverted gnomes — all this is very entertaining. There is a good balance between sexual and plot-driven scenes. Unfortunately, the three following parts have nothing to do with the first, apart from the visual similarity of the antagonists, the school as a place of action, and some kind of connection between tentacles and plants. At the same time, the visual style changes and the animation qualitydrops significantly. This is especially true for part 3, which has a lot of looping monotonous movements in three or four frames. The plot becomes very concise - so, the transition from the 2nd to the 3rd episode is not explained at all. In addition, in these parts eroticism is reduced mainly to the same type of sex with tentacles.

The 4th part stands out somewhat, as it attempted to summarize the plots of the previous two and included more unique designs of monsters, while at the same time remembering at least the most basic kinks (like spanking) that were present in the first OVA. This one is semi-entertaining, at best.

Three OVAs out of four greatly reduce the rating of the anime as a whole. I recommend watching the first part, which is really interesting and hot, and stop there.