The Mariko Aoki Phenomenon: Why Bookstores Make You Poop

Have you ever wandered into a bookstore or library, only to feel the sudden urge to defecate? If so, you’ve experienced a common yet mysterious mind-body connection known as the Mariko Aoiki phenomenon.

Normally, we associate spontaneous pooping with a cup of coffee or a big meal. But the Mariko Aoki phenomenon posits that merely stepping inside a bookstore is enough to trigger a bowel movement.

You won’t find the Mariko Aoki phenomenon mentioned in any medical textbooks. There is, however, a 9,000-word Wikipedia page dedicated to the topic and with dozens of tweets from people claiming that they’ve experienced “book bowels.”

So is there scientific evidence to support the Mariko Aoki Phenomenon or is it just an urban legend? As purveyors of all poop-related matters, we launched an investigation.

A Brief History the Mariko Aoki Phenomenon

In February 1985, a young Japanese woman named Mariko Aoki wrote an essay for the magazine Hon no Zasshi (“Book Magazine”) in which she confessed a bizarre recurring sensation: browsing books always gave her an urge to poop.

Soon after the essay was published, dozens of readers shared their own testimonies about their uncontrollable desire to take dumps inside bookstores. Hon no Zasshi struck while the iron was hot, publishing a magazine article titled “The Phenomenon Currently Shaking the Bookstore Industry!”

That phenomenon was aptly named “The Mariko Aoki phenomenon.” Nearly three decades later, it’s trending on TikTok—all because a woman from Tokyo was brave enough to expose her bowel habits to the world.

How Common Is the Mariko Aoki Phenomenon?

There hasn’t been any research on the Mariko Aoki Phenomenon since 2012. However, we’ve curated the highlights from a few obscure Japanese studies below:

• At least a few million people in Japan have reported experiencing the Mariko Aoki Phenomenon.
• As many as 1 in 10 people in Japan have to poop when they enter a bookstore.
• The phenomenon is between two and four times more common for women.
• People in their 20s and 30s appear to be the most commonly affected age groups, but anyone can experience it.
• The phenomenon is uncommon amongst “sporty males,” which we’ll assume is the same thing as jocks or bro-types.

This data comes from the Mariko Aoki Wikipedia page, so who knows how accurate it is. Nevertheless, it’s safe to say book bowels are a real thing, even if it only affects a few people.

Potential Causes of the Mariko Aoki Phenomenon

The list of explanations for this mystifying phenomenon includes scientific facts, full-blown conspiracies, and everything in between. If you’re inclined to go down the rabbit hole (or toilet bowl, rather) knock yourself out. For the sake of this article though, we’re covering the top four most-discussed causes of the Mariko Aoki Phenomenon.

The Gut-Brain Axis

This sounds complicated, but it’s simple: what you experience mentally affects your gastrointestinal tract. If you’ve ever been nervous and felt butterflies in your stomach, you’ve experienced the gut-brain axis.

When some people get nervous, however, their bowels spring into action. This can happen in places where you’re not sure where the restroom is located, an understandable fear if you have irritable bowel syndrome or a history of shart attacks. 

The gut-brain axis can also fire up when you’re overwhelmed with tons of information in places like museums, shopping malls, grocery stores, or in this case, bookstores.

The Smell of Paper and Ink

Some people suggest that the smell of ink and old paper and ink trigger defecation. However, it’s not those smells specifically that correlate with a bodily function, like an onion making you cry. Rather, it’s how your brain links those smells to a certain behavior—like pooping. 

Let’s say you have a habit of reading when you’re on the toilet. If you encounter a strong smell of paper and ink (like there is in a bookstore) your brain might think it’s time to do your business.

Your Posture

You might have forgotten how bookstores work if you haven’t been since elementary school, but you need to squat, bend, and twist your torso to find what you’re looking for on the bookshelves. All this maneuvering revs up your intestines, potentially causing the urge to poop.

Conspiracy Theories

The most outlandish (and entertaining) speculation is that the publishing industry is in cahoots with the toilet paper industry. According to TP truthers, book printers infuse chemicals into paper that produce a laxative effect when inhaled, thus increasing the demand for toilet paper. 

If you know us, you know we have beef with the toilet paper industry, so we won’t defend them here. All we’re saying is there’s far more nefarious things big TP does that are already proven, like injuring rectums and causing brawls inside supermarkets.

Feel Constipated? Find a Bookstore

Whether the Mariko Aoki phenomenon is legit isn’t as important as whether it affects you. If you’re plugged up, there are dozens of remedies like laxatives and overnight colon cleanses. But those will cost you at least a few bucks.

If your colon is full but your wallet is empty, look for the nearest Barnes and Noble. Just remember to pack some DUDE Wipes. And please, for the sake of the next person, do a courtesy flush.