Make Believe Mailer #141: AI Scream!
"YAJU&U," AI Music And Mass Meme-ry
One of the biggest Japanese songs of the year is clearly AI generated. It’s also about cumming.
“Iku iku iku!” goes the opening to “YAJU&U,” with the Japanese for busting delivered over a downright goofy synthesized string arrangement. The voice offering this all up sounds heavily processed, especially when half-a-dozen more join in come the chorus. The accompanying artwork (above) isn’t quite as blatant in its generative nature as, say, the sort of uncanny humans selling you fake watches on Facebook, but it still looks pretty janky when you start looking at the details. Though hey, there’s no trying to pass this off as human made by uploader Mochimochi — the “composer” is Udio, a song-generating platform.
“YAJU&U” is one of Japan’s largest TikTok-powered hits of 2025 thus far, which means it’s also one of the biggest songs in the country’s musical ecosystem too. Originally released in 2024, an upwind of attention at the end of last year set it up for a breakout this past spring, climbing to the number-one spot on Spotify Japan’s Viral 50 playlist (knocking off the nation’s global smash to date in the process) and staying there until just a few weeks ago. Even then, it lingers in the top five and still stands as a defining online hit as the calendar’s first half nears conclusion.
Which also gives it a more dubious honor — it’s the first generative-AI-powered song to become a true hit in Japan, and one not pretending to be made by humans, unless entering prompts into a text box can be spun into artisanal work. That’s a big development in the world’s second biggest music market. Cue the X threads and worries about culture becoming a trough of digi-gruel.
Yet one must also consider the central theme of “YAJU&U” to understand the full picture of what it means. This is, primarily, a song about ejaculation, and there’s something even more familiar at play within that explains the actual function of AI music worldwide.
But first…some terrible AI song about Chicago Cubs’ pitcher Shota Imanaga.
Stuff like the above mumble-mouthed baseball tune is primarily what “AI music” in Japan sounded like in the wake of Ghostwriter977’s “Heart On My Sleeve.” I mean, that and the assorted background music flooding Spotify and other streaming platforms, but that’s nothing new. Everything in this country seemed either extremely cheesy or vaguely funny in a “Homer Simpson and Peter Griffin sing ‘Ballin’” way. Though even then, it was people overseas making…everyone cover YOASOBI’s “IDOL.”
For a while there, “AI music” was more of a far-off concept than anything actually getting serious attention in the country. And generally speaking, generative AI used for “artistic” means got side eyes from netizens across the nation. Nobody outside of the tech industry liked McDonald’s “AI French Fry” short or the piano-tuning company giving it a whirl. Those, ultimately, were just bites at virality which didn’t work. They wish it approached the eyes focused on “loving cartoon family eating fast food.” Same goes for music videos entering the arena of wavy visuals.
Yet it changed in 2024…sorta. Eventually the AI tech capable of creating a song from just a few details improved, and users turned their attention on recreating one of the last decade’s most online-centric sounds.
“I found…something a bit scary.” So starts a tweet from derax456 (who, kinda ironically, collects and DJs primarily using CDs from the ¥100 corner of stores) that introduced Japanese music fans and beyond to a wave of AI-generated city pop starting to proliferate on YouTube. Some collections like the above disclosed how they were made, while others like the highly popular “A Chill and Emotional Playlist Perfect for Night Drives🚙” downplay and obscure its generative origins…but also c’mon. The focus fell on the sound…which many, including derax456, thought amazing in how it replicates the sonic idea of ‘80s Japanese pop, or at least one nook of it.
This sparked debate about AI ethics, but also deep dives into these glistening generative offerings. Yuji Shibasaki penned the best for Mikiki, offering both a musical analysis, breakdown of why AI creators gravitate towards it, and the very slipperyness of what “city pop” even is in the first place. It ends with the observations that a lot of interest in this stuff boils down to active vs. passive listening — do you look to songs as a celebration of human artistry, or as background music to help you finish spreadsheets at work? It makes sense that a style consumed by many in the 21st century primarily as a “vibe1” would be a good genre to use as a test case in the social-age’s search for its own Buddha Machine.
I think there’s another element to it, though. “City pop,” whether lived through or imagined, is something tied to the past, and it has become an idea with defined points one can latch on to and recreate how they see fit. It’s a meme.
Which would explain “YAJU&U” perfectly — it’s AI, sure, but the reason it’s popular is something much more familiar. And much more bizarre.
To some, you will look at the above face and have zero clue who this dude is. For others, you have instantly recognized maybe the most famous meme in Japanese internet history.
This is Yaju Senpai, a character from the 2001 gay adult video Manatsu No Yo No Inmu (A Midsummer Night’s Lewd Dream). It’s sorta a Rosetta Stone to understanding Japanese internet culture.
The film landed on the nation’s radar in 2002 due to a scandal, when it was discovered that dynamite college pitcher and expected top pick in that year’s draft Kazuhito Tadano starred in the first chapter of said flick, resulting in nobody wanting to go near him2. That was plenty juicy, but then 2chan users actually watched the movie — and found it was full of absurd situations and terrible, bad acting coupled with bizarre phrasing. These became go-to catchphrases on Japanese bulletin boards, and mutated into video memes on Nico Nico Douga. If you want a greater crash course in it, Know Your Meme has you covered, along with a few non-explicit screenshots.
Yaju Senpai has become the defining character from it, though his chapter from the movie didn’t arrive online until later in the Aughts. He’s evil in the context of Manatsu, but also talks in such a fast and awkward way that he seems very goofy3. When he’s having sex especially, he REALLY goes for it, as no shortage of memes have zeroed in on over the years.
He’s like…Nico Nico Douga’s Sarcastic Wonka maybe? Yaju Senpai is tied forever to the Japanese web, and has travelled beyond its borders. Seeing as how 2chan and Nico Nico Douga helped shape other Asian internet cultures (at least among otaku types), people across the continent also know who he is. Here’s a video of a crowd in China shouting quotes from a gay porn back at a host and holding up photo stills from the movie. People still meet outside of the house where this was filmed to celebrate central elements of internet culture4.
Yaju Senpai never left, and “YAJU&U” is all about him, loaded with references to his arc in Manatsu (including the number “114514” a numerical reference to…one of his lines? Nico Nico is built different). Goofs not far off from this have been made for nearly two decades now — here’s a short fanmade anime, and let’s not even get into people using this character’s name to prank sports announcers. This song is simply continuing that lineage.
What’s changed is the speed at which memes can come together.
We’re heading to a place where a divide between “OK AI” and “Not OK AI” becomes more clear. At the moment, generative-AI for the use of creating art is, at least in certain corners of the internet, seen as unethical and very bad. Yet I can’t shake that everyone I know in real life uses AI for some kind of menial task daily, and nobody bats an eye at it (including me! I use programs that assist with transcribing interviews). Not many want to see “AI movies” in theaters or “AI rap” on top of the Billboard charts…but I think a lot of people welcome it easing the annoyances of the everyday and helping to get things done.
Memes fall into this latter situation. “YAJU&U” isn’t at first brush art, and I’d think most in Japan would agree. It’s part of an online continium stretching back to 2chan, less a disruption and more a new twist on a familiar favorite. There’s a dash of nostalgia here too, kind of like what was seen with the city pop revival. Younger generations who were born after Nico Nico Douga was founded have embraced the number…and are the ones who created the adjacent “Yaju Senpai Dance,” which turned the song from an Aughts-era joke to a genuine phenomenon5 and made it hit it is. On the plus side, there’s a strong human element present here.
So it’s all an internet joke. But…it’s also one of Japan’s biggest domestic hits if going off data and greater zeitgeist presence. That makes it a significant moment in AI music, and what it’s capable of when presented in a specific way, especially when tied to the speed of memes in the 2020s. The lines start to blur, such as with the whole “AI Ghibli” ruckus a few weeks back, which at its core is no different than Simpson-fying yourself but presented much more perilous creative and legal questions6. What seems like internet detritus at first mutates into something much more noteworthy.
Since “YAJU&U,” I’ve noticed a big uptick in AI-generated content. A lot of it is Yaju-centric, including a whole channel devoted to the premise of it along with actually sorta clever “clean” edits on the song (“iku” becoming “niku,” the Japanese for meat…for a BBQ!). Yet there’s also new varieties of AI music getting a fair amount of views on YouTube…fake pop songs, numbers touching on current events, unsettling versions of modern idol cuts.
None of it is that serious, because the most popular generative-AI products worldwide right now are just memes, produced at the pace of email responses and online searches. What happens, though, when those works gain so much momentum they become the engine of music to many?
“YAJU&U” points towards a future where this question has to be answered. For now, though, enjoy the silliness and remember the good times where this is just a bizarre hit song based on foundational internet culture, and not a peak into what’s to come.
Written by Patrick St. Michel (patrickstmichel@gmail.com)
Twitter — @mbmelodies
Check out the Best Of 2025 Spotify Playlist here!
Yes, yes I know this isn’t everybody, but seeing as how many playlists — robot or human made — on YouTube boil down to “Tokyo Neon Night” or “Driving In A Showa Anime” I think it’s fair a lot of people use this as “Hi-fi Economic Pop For Nostalgic And Escapist Purposes.” Look, I’d kill to experience this video in real life too, I get it!
So this is also a pretty early example of doxxing on the Japanese internet.
For transparency sake, I have not actually watched the movie, only seen clips of the characters talking.
A new-to-me discovery…Peanuts-kun riffing on this seven years ago.
Worth noting that it’s popularity has sparked backlash, with many worrying about younger kids and teens dancing to a song that’s super raunchy (though I think the youth know what they are doing…it’s provocative). It has also started some talk over concerns of everything about it being like a degree away from mocking gay people, which is something I’m not versed enough to comment on but does, to some degree, feel like a leftover from the edgy Japanese internet of the 2000s.
That whole happening is much closer to AI City Pop than “YAJU&U.” Really, I think it’s hilarious that the Ghibli debate played out at a time when the leading AI case in Japan was about gay adult video characters.