So, working just fine in real life, then…
Even before the Internet, mail order was a thing.
AFAIK the great majority of people with this fetish want to wear the diapers themselves.
Well sure, for walking around in conventions. Even the best of the cosplay costumes aren’t designed for having wild hybrid sex. Banging away at your arctic fox partner, you open your eyes and see their head half off, they can’t see out of the eyeholes, and it’s hard for them to breathe because the mouth hole is buried in the blanket and it’s 125F inside the costume. If that’s the way hybrids had sex, no wonder there are none of them left on the planet.
Are you speaking from experience?
Just once, but yes. Thankfully we both had a good laugh about it and then went to Plan B. The laughter kept popping up though.
That’s not what hentai means. Even fairly vanilla anime and manga porn is hentai.
There was that guy who skulked around the U. C. Berkeley campus sometime in the mid-1970s who was into sneaking up behind women and sniffing their butts. Several women reported it (and there may have been other witnesses?) but I don’t recall if the guy ever got caught.
But there was a mini-fad of people selling, and wearing, T-shirts with a picture of someone sniffing a woman’s butt, with a circle around it and a big red slash over it.
Public butt sniffing on unknown, unwilling women? I’d like to think that was a one of a kind type of thing, but knowing guys and their power to turn anything sexual, I’d guess it’s in the uncommon but not unknown category.
Not a fetish ( I don’t think) but Senegoid’s story reminded me of a weird thing from back when I was about 10 and lived in the sticks. The nearest town had a population of about 4 or 5 thousand. One summer, a guy, always dressed in a grey hooded track suit, would hide and jump out at 18-25 year old women and just knock them to the ground and run off. No molesting, no stealing, just knocked them to the ground and ran off. I think it was about 10 women over that summer, and it didn’t happen again, but he was never caught.
This thread keeps bringing to mind the wise words of Lore Sjoberg:
Feeling down? Depressed? Alienated?
Just remember these three words:
"I’m somebody’s fetish."
If one of them had cut a long fart with a God-awful stench, it might have cured him! LOL
That’s not what it means in Japan. In other countries a lot of people use it to mean tentacles.
…and a lot of people in other countries, correctly, don’t. I, for instance, am not in Japan, and neither are my friends, some of whom are quite into hentai - not my kink, but whatever works for them.
But if you want to keep using it to mean only tentacle porn, go right ahead. Just be aware there are a lot of people who may, correctly, say there are into hentai but are not tentacle fetishists.
And those people need to be aware that a lot of people they say that to will think they mean tentacles. 
I don’t get how ‘manga porn’ can be a fetish anyway. It’s just porn, but with drawings instead of photographs. If you enjoy a photo of something, you’d also enjoy a drawing of it, no?
They know, they’re not living in a cave. They don’t care - or rather, it’s a feature, not a bug. Being in the right versus mundanes about the minutiae of their subculture is the kind of thing geeks love.
Speaking for myself - no. Manga doesn’t register as realistic to me. Obviously many people’s mileage varies.
I’m not in Japan either, and this is the first time I’ve ever seen someone equate hentai with tentacles except in the “oh, freaky stuff, like tentacles?” sense. The term “tentacle porn” exists in English for a reason, that reason being “hentai” generally isn’t understood to mean tentacles.
Oh my sweet summer child! You really are entirely flavored with the extract of the fruit of an orchid, or the derived chemical compound, aren’t you?
Yes, but it’s not really a good thing because it attracts a lot of insects.
I used to work in a building across from a Dallas-area hotel that hosted something called the “Furry Fiesta” every year. Based on some of the costumes and behavior we saw at restaurants and people going to/from the hotel, it sure seemed to be working for them.
I’ve told this story a time or two.
Background:
Crewmembers who are based in some city but didn’t live in that city are common in the airline industry and are called “commuters”. Typically they try to leave home early in the morning, fly to the base by midafternoon, and work the rest of the day into the night. Then fly around the system for a couple/few days. Same thing at the end of a multi-day trip; get done working in base early enough to ride home to wherever that same day. And of course if they can’t get a schedule that starts late and finishes early, they’ll end up needing to commute into the base the day prior and sleep over someplace before starting work the next morning, or vice versa at the end of a trip.
Story:
There once was a hotel near the airport in St. Louis. It was older and a bit of a dump, which meant it was cheap. Which meant it was popular with commuters who just needed a place to flop for 6 or 8 hours before leaving for home or work the next morning.
This hotel was also home to the Midwest BDSM Society’s annual week-long convention: “Beat Me in St. Louis!”
Many … interesting … tales were told and retold about crewmembers’ stays at that hotel during the convention and their interactions with the conventioneers. Them folks be strange an shit! But ref @bump above, it sure seemed to work for most of them.
Sadly the hotel was torn down 20-ish years ago to make way for an airport expansion. I don’t know where or whether Beat Me in St. Louis is still held. But I bet Google does. 
You saw them having sex while wearing their costumes? Most places frown on that sort of stuff, which is a fetish all by itself.
From some of these posts, I think some people don’t understand that a fetish is all about the sex part. If a man has a large collection of women’s shoes that he masturbates on, that’s a fetish. If he has a large collection of shoes because he thinks they are nice looking, he’s a shoe collector. Furries at a con is not a fetish, it’s cosplaying. Furries having sex in character is a fetish.
But BDSM is really easy to do in real life, no reason it shouldn’t work for anybody that’s into it. You don’t need a complicated costume or specialized equipment to do it. It’s probably near the top of the list for real life workability.
Wearing a crappy bunny outfit while hopping down the bunny trail with your girlfriend while she, I don’t know, makes bunny noises and tries to bite you with fake little bunny teeth while wearing a too large bunny head, is something that does not work well in real life. Is it doable for some people? Sure. Is it anywhere near the real life workability of other fetishes? No.