Quick heads-up if you're expecting a professional review: This ain't it. These are just my unfiltered and honest thoughts on this show. May or may not contain spoilers, idk.

Oh boy, where do I start? Well, let me explain why I even watched this because there is a shitload of reasons, it almost seemed to be that the universe just really wanted me to watch Onimai. At first it was multiple recommendations on YouTube of people putting out their own, surprisingly positive thoughts, considering the show’s premise and how it is presented. In addition to that a few days ago I also stumbled over the OP of Onimai (more about that later!) by virtue of the rhythm game osu! and because apparently that was not enough, a mere 48 hours ago I got hired to do some typesetting/translation work on some... let’s call it a questionable spin-off manga of Onimai (Anybody got some bleach for me?). And lastly, I am just a dirty degenerate sometimes.
Needless to say, it seemed like all of this was a sign for me to check out the series itself, and despite knowing a few things about the show already, I was as ready as one could be to dive in.

Right off the bat, I noticed how unlike some other shows with seemingly similar characters (looking at you, Eromanga Sensei) here they generally act like somewhat real people, not being constantly ridiculous, something that I really appreciate in Comedy-Slice-of-Life series (because unfortunately too many shows tend to go way too over the top with this!). Maybe that is because of the cast being basically all female? Well, technically female that is.
Which brings me to my next point, our main character Mahiro. We never see him in his previous male form, and I think that was actually a smart idea as from the very start, despite his attempts to be manly and “reject” his new feminine form, he doesn’t seem to be very masculine at all and he also never outright or strongly objected him being a girl now. Also now being perceivably the younger sibling in the Oyama family it just really fits his whole personality, being usually lazy, obsessed with playing games and so on.
Then, the other characters. Overall, I think they’re all alright with their own personalities, although I do feel like some (Miyo) don’t really serve a real purpose and others (Mihari) I feel like we could definitely use some more background on. It’s probably best for me to just go through each character individually since I really kinda want to share my feelings about them:

• Mihari – we get very few background info about her past, mostly just from years back when she was clearly the younger sister in the sibling relationship, with her looking up to her older brother. But I feel like the entire story just lacks explanation of the more recent past. What’s up with their parents, do they literally have no communication with them (they must at least be calling from overseas every now and then, right? And then, how would they explain the Mahiro situation? Surely as a Hikikomori he’s at least keep up some sort of phone- or video call communication with their parents as well?). Also, we get she’s a genius but her whipping up an experimental gender-bending drug one day but then no further explanation what kind of research she is actually doing? Kinda whack.
• Kaede – I think she serves well as another big sister figure and from Mahiro’s interaction with her it just cements that being a younger sibling just seems to be Mahiro’s true destiny. Other than that, no strong feelings about Kaede, except that they could’ve easily toned down the jiggle physics a little. More on that later.
• Momiji – the best friend character. She is definitely something that Mahiro needed in his / her (I’m sorry, I just can’t go on talking about Mahiro as a male, we only ever see a girl in the show after all!) life. Other than the fact that she gets easily and overly jealous at times, I think she’s a great character although not outstanding.
• Asahi – Just an absolute energy ball and klutz. She’s fun, perfect addition with Momiji.
• Miyo – relatively boring character in my opinion. Even after just like 12 hours after watching I only remember her as the closet pervert with big honkers.

So yeah, I guess I mostly like the cast!

Something else, art and audio!
The whole thing is generally very beautifully animated with some exceptions being some looping animations which just have a bit of an odd feeling to me. The pastel color palette is absolute chefs kiss, perfectly reaffirms the girly vibes (shit that makes me sound weird, doesn’t it?)
As I have mentioned in the beginning of my review, I said I touched the anime’s opening in osu! and usually these upbeat anime songs have a 50/50 chance of me liking them or absolutely hating them, this one’s fortunately quite the banger. The ending is also good, but I definitely skipped it half of the time. Now voice acting! With my limited knowledge I’d say it was pretty good, can’t say much more, however Mahiro’s occasional squeals are what really got me. I don’t know why but they fit so perfectly like???

Lastly, my gripes with the show (because so far as you can see, I am super positive about it!)
The obvious one is the overly sexualization of young girls. I can’t and never will understand why this seems to be a such a common thing shows of this genre tend to do. However, I feel like I can kind of let it pass in some scenarios here as it does indeed serve a bit of a purpose here. Imagine for a second (assuming you are of the male majority of anime-watchers), one day waking up as a girl and over time having to get adjusted to everything (and I mean EVERYTHING – actually touching the subject of a girl’s puberty and all that comes with it is a bold move but gives the show a bit more seriousness than your average slice of life comedy shit).
Other than that, I’m just not a fan of shipping in anime when it doesn’t serve any purpose in the show, but that’s not the worst thing

Guess that’s actually it, huh?

I'll be back for more questionable and controversial anime reviews, someday...