The newest book from the super-popular monster girl author! Experience pleasure that humans can't by transforming your childhood friend into a soft-winged harpy and a mermaid in a slippery school swimsuit, and turn your underclassman into a tentacled scylla using a mysterious app that turns human girls into monster girls!❤

When you're done reading the popular "Monsterization Application" chapters, don't skip out on all the other monster girl love stories and school transformation sex scenes this book has to offer! There's a descendant of Kiyohime who's self-conscious about her serpent form, a slime girl who turns into a sexy teacher, and an oni girl who looks great in black tights!

Monsterization Application has a story by and art by Horitomo. English translation is done by Jumi and lettering by Bryan Montesdeoca. Published by J18 (March 4, 2026). Rated M.

Lucas DeRuyter
Rating:

Your enjoyment of Horitomo's Monsterization Application manga will entirely depend on whether you have the soul of a monster fucker. If the idea of a guy having sex with a spider lady doesn't pique your interest or stimulate you in one way or another, you shouldn't put your time, attention, or money towards this title. However, if the scenario described above fills you with even an ounce of curiosity, you should probably read Monsterization Application, as it's one of the better pieces of monster fucker manga available for purchase in the English language.

The premise of much of Monsterization Application is that shy boy Shintaro discovers a mysterious app on his phone that can turn real-life women into monster girl fantasy creatures. His childhood friend Kanako volunteers to help him test the app, and through copious amounts of fantasy fornication, they're able to start the romantic relationship she's always wanted with him. There isn't much of a central conflict in the main narrative of Monsterization Application, but the characters are cute enough together, and the scenarios are inspired enough that I don't mind that the leads' dynamic is largely stagnant by the end of the first chapter.

Where Monsterization Application's writing does shine, though, is in how thoroughly it explores the different kinks afforded to each kind of monster girl. There's harpy egg laying, scylla tentacle group sex, and making use of the aforementioned spider lady's spinnerette orifice for purposes other than spinning a silk web, to name a few! There's enough novelty in here that even longtime readers of monster fuckery smut will find something to appreciate, while still being approachable to those curious about the genre.

If I had to elevate one main criticism of Monsterization Application, it's that this work is firmly grounded in the male gaze and overtly written for a presumed male, cishet audience. One of the side stories in this work focuses on a polite young man having sex with an anthropomorphized version of his pet cat, and no amount of proficient and creative artwork or thoughtful dialogue can make this scenario feel not scummy to me. We live in a post-Guillermo del Toro's The Shape of Water world where women are more vocal than ever about how this particular kink appeals to them, and it'd be nice if Monsterization Application threw in one or two monster dudes to balance out all the monster girls.

While it could be more inclusive in its perspective, Monsterization Application is thorough in its exploration of the parts of this kink that it does focus on, and anyone who vibes with it will have a good time with Horitomo's latest manga.

Erica Friedman
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According to Dana Oswald in Unnatural Women, Invisible Mothers: Monstrous Female Bodies in the Wonders of the East, “the Anglo-Saxon listing of monsters in the Liber Monstrorum carefully divides its monsters into three categories: monstrous men, monstrous beasts, and monstrous serpents. This text demonstrates that those creatures that possess both animal and human features, such as fauns, sirens, hippocentaurs, and the cynocephali (conopoenae), are still considered human. Monstrous humans are not to be identified as animals; they are, rather, incomplete or over-determined humans.” I found myself thinking about this as I read Monsterization Application.

The girls here always remain human enough to have a vagina, so penetrative sex is possible, and the machinations of that with Lamia's serpentine body or an arachnid girl were actually vaguely interesting. Female monsters have been sexualized pretty much throughout history, so the idea that someone might find a Scylla or a slime sexually attractive isn't that far from the classical Japanese sexy octopus. I'm a little less convinced by the sexy Harpy, but I do appreciate the creativity.

The art isn't bad for porn, honestly. As I said, the creativity of the transformations was unique, and the characters all seemed to be enjoying themselves, which is always a strong point. Yes, breasts are distended in ways that look painful, vulvas and penises look uncomfortably gorged, but that's kind of par for the course in manga like this.

As I read, I found myself thinking about the lines humans draw between creatures being “monster” or human”. I'd argue that these non-human bodied girls are more human than the human-bodied characters in 18+ manga whose goal is to hurt, demean, or debase women. So sign me up for more monster porn…at least these (beast)people like each other and are having fun when they have sex. That goes a long way to making something “good” in my opinion. Now excuse me while I reread this article about a Gorgon….

Bolts
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If you like monster girls, I have a collection of stories for you! A lot of these volumes usually revolve around a specific theme or fetish. In this case, we're dealing with different types of monster girls. I was very impressed with the initial conception of the first couple of chapters because there is actually an episodic story here mixed in with a few chapters. The initial setup is just about a young couple who discover an app that allows the boy to turn his girlfriend into a different monster girl each chapter. It runs through the usual suspects like harpies and lamias, but there's even an occasional curveball thrown in there with mermaids and spider girls. I could've read an entire anthology of just this couple because I did like their chemistry, there wasn't really a lot of fighting, and the sex scenes were actually quite creative. I appreciate an artist who frames scenes or takes advantage of the fact that most monster girls do have different anatomy and therefore wouldn't have sex the same way as regular people do.

The one-off chapters focus on regular people just casually coming across monster girls that just happened to exist in the real world, but they're not as strong as the couple's chapters, and there are fewer creative setups thrown in here, like with cat girls. I'm also not a big fan of the way that this book organizes its chapters because it will start off with that main couple that I mentioned, and then transition to a one-off chapter about completely different characters before eventually going back to the main couple. It would've been better if the book had just gone through all the chapters with the main couple first before it started getting into the one-offs. Plus, the story of the main couple concludes with an illusion to potentially a greater thing going on with the app that almost felt like it was opening up a larger story, but it never gets brought up again by the time I got to the end of the book. So it does feel like there are a couple of missed opportunities here that the book doesn't explore thoroughly, but on its face, there is definitely more than enough here for monster girl lovers.