I'll be talking about porn. You can stop reading now if you like.
Before he became the successful professional writer/artist of monster girl manga (Daily Life with Monster Girls, 12 Beast, Deadline Summonner), Takemaru "Okayado" Inui was just another artist on pixiv, a Japanese online artists' community. He drew hentai. It can be found online and I've read it. It also has monster girls, of course, and some of it's quite good. You can see his evolution towards what his professionally published work, but in some ways some of that earlier hentai arguably surpasses it.
I've found two series, although there's probably plenty more I missed. I also don't know when he drew it all, with 2008 being a guess. My first short Okayado series is Monster Musume Report (8 pages, forgettable) and my second is Living With [????] (16 pages, much more interesting).
That said, though, this is a chunkier body of work than the raw page count might suggest. These are big pages with lots of panels, each one the equivalent of several pages of weekly manga. Monster Musume Report has 11-21 panels per page, while Living With [????] has 15-25 in fully painted colour, which I'd say is the equivalent of about ninety pages of Daily Life with Monster Girls.
Firstly, Monster Musume Report.
They're a bit rubbish. They're an early attempt. They're passable for what they are, I suppose, but they're basically just porn. There's not much reason to read them except for looking at sex, although they do have some personality and they're certainly far more interesting than non-comics pornography. (I have a theory that comics are the best medium for intelligent porn, since they actively encourage creators to keep up the dialogue, characterisation and plot even during hardcore sex scenes. The word balloons don't slow down the pictures.) Anyway, the formula for Monster Musume Report is:
1. "Hello, my name's John Smith and I'm a monster researcher."
2. John gets captured by his monster of the week, which fortunately leads to sex instead of, say, getting killed and eaten. This is empty and unconvincing, being porn, although I like the examination of monster biology and habits.
3. A punchline of some kind.
The centaur two-parter includes a close-up of a horse's vagina that looks like a medical textbook. It's as sexy as roadkill. Don't read while trying to eat. The non-story and unconvincing characters add up to almost complete worthlessness, but the accidental humiliation punchline is quite funny. "Waaaah, no, umm, I mean compared to a centaur's. It doesn't mean you're small compared to humans..."
The lamia page is again wafer-thin with porn characterisation, but the snake biology makes it a bit more interesting. "Snake mating can take many hours. In some species, it can take an entire day." Lame ending, though.
The harpy page is daft enough to be funny. The birdbrained harpy carries John off as prey to feed her chicks. Whoops, she'd forgotten she doesn't have any. So let's mate! I was also amused by John freaking out at the harpy eating her own (unfertilised) eggs.
There's an odd two-parter with a carnivorous plant (Alraline) and a butterfly girl (Papillion). I suspect Okayado read up on the symbiotic relationship between a carnivorous plant and a species of ant in Borneo, then used it in this manga. This pair are currently the only monsters from any of these strips not to have since appeared in Daily Life with Monster Girls, by the way. Involves lesbianism, fellatio, a boob job and a butterfly proboscis being inserted into John's urethra.
Finally there's a two-parter with Slime. She already has the head-blob-tentacle! Slime's great, but this barely counts as a story.
Secondly, Living With [????].
What's charming about these stories is that they're about relationships. Our unnamed hero is the monster girl's devoted boyfriend... and, despite appearances, he's not two-timing them. There are eight heroes who look the same. They're brothers. Each working hard to cope with new lifestyle problems of his monster girlfriend, which is how each story will start. It won't be about sex, but about the domestic arrangements you need if you're rearranging his life around a girlfriend like this. Moving house to somewhere close to her natural habitat, for instance, or driving for hours every week to somewhere she needs to go. It's sweet. As a result, the sex just feels like a more intimate look into the relationship, while also being wildly preferable to the harem antics of Daily Life with Monster Girls.
For lack of anything better, I'll call our hero(es) Kimihito.
Living With Arachne (2 pages) looks a lot like cohabiting with Freddy Krueger, or perhaps Edward Scissorhands. Arachne's sensitive and can freak out on realising how badly she's hurt Kimihito, but that didn't stop her from carving him up in the bedroom like an Aztec sacrifice. It's amazing and sweet that he's still with her (and alive). Even the fact that she's sexually insatiable isn't all good news from his point of view.
Living With Centaur (2 pages) shows a somewhat complicated relationship. Centaur's a bit proud and prickly. They're walking through the countryside and Kimihito wants to ride on her back, but Centaur reacts as if he's asking her to do something filthy. Ironically, this is the closest these strips get to the reality of a man trying to talk a reluctant girl into sex, complete with Kimihito being underhand and a bit of a bastard about it. (Don't worry, he pays in the end.)
The centaur sex is more plausible this time, by the way. Kimihito doesn't use his penis, but instead his entire arm.
Living With Dullahan (2 pages) is peculiar, but in a good way. I liked it a lot. It's alarming and inconvenient for your girlfriend's head to keep falling off, even if she never seems particularly worried. At such times, the body keeps going and does its own thing. It turns the relationship into a sort of threesome, with a complicated sex life. I liked this story. It also gets some heartwarming darkness from the fact that Dullahan's an embodiment of Death, so her presence in Kimihito's life theoretically means he's about to die. In practice, Dullahan keeps a lookout behind his back for Grim Reapers and is liable to attack them with their own scythes.
Living With Harpy (2 pages) ends up with the usual eggs situation, but most of the first page is simply about Kimihito helping her with her flying practice. "Two or three times a week, harpy and I go out to an open field for her flight training. It's an hour's hard ride by motorcycle, but she sings happily, so it's no big deal."
Mind you, the egg-laying is basically a childbirth scene, even if Harpy's about to eat them. (How does she know they're not fertilized, by the way? She's having sex with Kimihito and even he says that they could theoretically have been their children.)
Living With Lamia (2 pages) again puts Kimihito through the wringer. For starters, he's had to buy a pick-up truck from overseas and tear off the roof in order to have a vehicle that can comfortably carry Lamia. More gruelling, though, is the real ordeal. "One round of sex with Lamia would take more than six hours! To do that, I'll need lots of endurance and a heavily trained spirit, because six hours is a long, long time." He does weight training. He does martial arts meditation. Three of his ribs break when she constricts him. Bizarrely, though, this is sweet. The difficulties make their affection feel real and make them seem like a real couple.
He's also endearingly depressed when she's hibernating. "I can't help but feel lonely. And though she told me 'if you feel like doing anything, go ahead', it's useless." (Yes, that means what you think it does, as she lies there dormant and naked, but he just sits there fretting.)
Living With Mermaid (2 pages), rather quaintly, puts Mermaid in a bikini top. It won't stay on, obviously, but that's more modesty than one could argue is traditional for mermaids. This story threatens neither life nor limb, but it ends amusingly when two Kimihito couples accidentally meet. The timing is unfortunate (i.e. mid-coitus), but that just makes an over-enthusiastic Lamia quiz the mortified Mermaid on sex tips.
Living With Minotaur (1 page) shows our hero as a farmer. "Living within our means has been difficult, but we do have an additional source of income." What might that be? Answer: healthy farm produce! "If a Minotaur doesn't have her breasts milked regularly, they become swollen and painful."
Living With Slime (2 pages) is the wackiest story. Slime is cute, but freaky. Her biological composition, her nutritional needs and how she responds to being watered all need explaining to us. Sex with a slime sounds bizarre, although one can see the appeal. "Technically slime doesn't have any orifices, but at the same time her entire body is one." However there's a downside, demonstrated in blood when Kimihito makes the mistake of losing consciousness. "Since she can receive nourishment from anywhere on her body, I try not to stay in contact with her for too long, or she might start digesting me."
Don't worry, though. He lives.
Oh, and there's a throwaway extra page, Meet The Author, in which the manga-ka talks to a Kimihito.
In short, it's quite impressive. Monster Musume Report is of little interest except as a developmental stage, but Living With [????] will make you wish people could be a little more relaxed about sex in entertainment. I really rather liked these intimate little relationship vignettes, especially if you consider how much they're achieving in the space of two comic strip pages.