Review of Villainess Level 99: I May Be the Hidden Boss but I'm Not the Demon Lord
Level 99 is an otome isekai where a girl is reincarnated as the villianess, and decides to make the best of it by grinding to level 99. The other characters are like, wow, that's crazy haha. And that's the show. Not to say it's bad, but that's pretty much the whole thing. The character development is lacking, and the plot is one-note. It's more of a cute loner girl does cute things show, and everyone around her thinks she's so weird and scary. Most of the other characters are quite rude for a majority of the show, which is to be expected from this villainessisekai subgenre, but I found annoying. Another thing to note is that the titled villainess doesn't do much villainy, or have much of an ill intent towards others, which I usually look for in these kinds of shows. She is in the "role" of the villainess, but isn't necessarily a villain.
I enjoyed watching this show, and I had a good time watching it. Those are the most important things to me, and if you are already enjoying "villainess" trope anime, you will probably have a good time watching this show. If you take this show too seriously, or if you aren't familiar with the villainess collection of tropes, you may not enjoy it as much. I wouldn't recommend this to someone who isn't familiar with the subgenre.
Anyway, if you're looking for something casual to watch, and you already like spoofs of otome isekais, you will probably enjoy this. If you're looking for something more serious, look elsewhere. I rate 5/10, since it is enjoyable if you already like the niche, though not very memorable.