Sexy science experiment tests one of Japan’s most persistent pieces of folk wisdom.
Like any country, Japan has its own collection of folk wisdom, with some pieces of oft-repeated advice not really meshing with actual results. For example, eating stretchy mochi at New Year’s, for example, is supposed to grant you a long life, but actually has a pretty good chance of killing you right then and there.
And then there’s Japanese men’s favorite bit of sage knowledge: rubbing a woman’s breasts will make them bigger. Granted, this isn’t something Japanese schools teach in biology or health class, but there’s no shortage of dudes in Japan who’ll insist, usually in hushed tones over beers with the boys, that rubbing a woman’s chest produces a bigger chest to rub, like some kind of perpetual-boob-generating system.
おや?もうお昼か!
— 安田七奈🍵なーちゃ (@nana_yasuda72) December 27, 2018
ひるなーちゃ🙃 pic.twitter.com/CuM7oECAyw
So as part of a New Year’s TV special, broadcaster TV Tokyo teamed up with Japanese bikini model/race queen Nana Yasuda (pictured above) to find out what would happen if the 27-year-old Tokyo native’s breasts were rubbed 10,000 times. The results were revealed as part of a program in which 10,000-repetition experiments were performed in various fields (including Japanese calligraphy strokes and .kendo sword swings), but, obviously, the breast research was of particular interest to viewers.
"ひたすら1万回"見てくださったみなさんありがとうございました☺️
— 安田七奈🍵なーちゃ (@nana_yasuda72) January 1, 2019
私よりもずっとずっと大変だったちなみんと星野さん本当におつかれさまでした‼︎
そして戸瀬先生ありがとうございました❤️#ひたらすら1万回#1万回ハウス pic.twitter.com/1mfH9NlPsh
However, it was determined that random squeezing might be detrimental to Yasuda’s breasts, and so TV Tokyo also enlisted the help of a “breast development counselor,” who devised a multi-motion cycle that began with firmly cupping the underside of Yasuda’s breasts and transitioning to palming and rotating them. A single 10,000-rub session was also deemed too heavy a workload for the model’s chest, and so the complete experiment would take place over the course of 12 days, with Yasuda herself handling the rubbing duties.
今年最後のひるなーちゃ!
— 安田七奈🍵なーちゃ (@nana_yasuda72) December 31, 2018
2019年もよろしくね😚❤️ pic.twitter.com/SvN676qruv
Along the way, Yasuda recorded her perceived changes. At 2,000 rubs, she noticed that her previously stiff shoulders felt much better. Once she hit the half-way point at 5,000 rubs, she said “It feels like my breasts really are getting bigger,” and 1,000 later, at the 6,000-rub mark, she said “My breasts are overflowing from my bra.”
▼ Yasuda’s 2018 Santacos video
ジングルベール🔔ジングルベール🎅🔔💫 pic.twitter.com/SFDIve0xks
— 安田七奈🍵なーちゃ (@nana_yasuda72) December 25, 2018
Once all 10,000 rubs had been administered, it was time to measure Yasuda’s chest, with the before/after being:
● Before 10,000 rubs:
Bust size (top measurement): 81 centimeters (31.9 inches)
Under-bust: 73.5 centimeters
Cup size: D
● After 10,000 rubs
Bust size: 82 centimeters
Under-bust: 68.5 centimeters
Cup size: F
So according to the program, rubbing Yasuda’s chest 10,000 times didn’t just make her bust two cup sizes larger, it altered the shape of her breasts too, adding volume at the top while compacting them at the bottom.
However, it might be a little early to go declaring this a monumental breakthrough in the field of boobology. Remember that the 10,000 rubs were administered over a period of almost two weeks, during which any number of other factors could have been in play, such as increased calorie intake (and the reduced shoulder stiffness Yasuda reported may have just been a muscle-stretching side effect of regularly performing the rubbing motions). So even if Hitosura Ichimankai’s results are legitimate, it’s not a sure thing that it was all the rubbing that produced them.
美容院行ってネイル行って今年の美容納め完了🤩‼️ pic.twitter.com/nwQnG7Z8R5
— 安田七奈🍵なーちゃ (@nana_yasuda72) December 30, 2018
There’s also the fact that proper science requires experiments to be repeated multiple times in order to verify the relationship between cause and effect, though if Yasuda is willing to devote herself to this research, odds are her fans won’t mind a bit.
Source: Shirabee via Nico Nico News via Hachima Kiko
Follow Casey on Twitter, where he’s wondering what sort of licensing process there is to become a “breast development counselor.”

Japanese swimsuit model’s dried fish bikini NFT series sells out, asking prices soar【Photos】
Family Mart Japan installs red-eyed “Monster Wolf” to keep bears away from convenience store
Starbucks Japan reopens Shinkansen platform store after redesigning it for speed
Tokyo cops arrest foreigner for suspected visa violation, don’t know what new residence cards look like
The adorable, delicious joy of the Totoro cream puff gift box[Taste test]
Japanese sweets brand creates new drinkable Cigare and we’re totally here for it
Japanese theme park adding Immersive Death Game with a “bomb collar” you have to wear
Japan launches first overnight Shinkansen bullet train between Tokyo and Osaka this summer
TKG Debate: What’s the best way to eat Japan’s beloved raw egg comfort dish?
Starbucks Japan creates special drink bottle bags, adorable stickers for all 47 prefectures[Pics]
Pikachu brings electric style to brand-new Pokémon G-Shock watch featuring every stater trio
Japan announces sudden 400-percent increase in visa fees for foreigners entering the country
Japanese ninja certification exam attracts 131 candidates from Japan and abroad
Studio Ghibli store Donguri Republic announces opening of first-ever store in America
“Phantom Egg Shop” opens in Japan, with a dozen rare Japanese varieties
Starbucks Japan releases new Frappuccino, tea and soda drinks for summer
Japanese sweets shop sells an ohagi so exquisite it sells out by noon
New Japanese overnight train coming to connect Tokyo with Tohoku in sleep-travel style
Uniqlo reveals third round of massive 100-year-anniversary manga T-shirts for Jump’s Shueisha
Even at twice regular Daiso price, this handy item is still great for summer travel in Japan
New official Ghibli anime food cookbook will teach you how to make Ponyo’s ramen and more
Forget Tokyo go-karts – there’s a new way to sightsee on four wheels in Japan
Japan’s human washing machines will go on sale to general public, demos to be held in Tokyo
Starbucks Japan releases new drinkware and goods for Valentine’s Day
We deeply regret going into this tunnel on our walk in the mountains of Japan
Starbucks Japan releases new sakura goods and drinkware for cherry blossom season 2026
Japan’s newest Shinkansen has no seats…or passengers [Video]
Put sesame oil in your coffee? Japanese maker says it’s the best way to start your day【Taste test】
Japan reportedly adding Japanese language skill requirement to most common foreigner work visa
Japan’s 5.3 million beautiful Hitachi Nemophila flowers are now in full bloom[Photos]