(CNN) — In Spain, residents of Barcelona and Madrid have each other to dislike when it comes to sport.
The West and East coasts of the United States have traditionally been rivals, though lately it's been the two coasts versus the rural middle (derisively termed "flyover country" by some) that defines the greater cultural split.
In Japan, a rivalry that can be just as fierce lies between the eastern Kanto region and western Kansai region, both on the main island of Honshu. Kanto is home to the country's modern capital of Tokyo and surrounding cities, including Yokohama, Chiba and Saitama. Kansai is home to its historic capital of Osaka, as well as Kyoto, Kobe, Nara.
The cultural contention between the two is so longstanding, and entertaining, that it's regularly discussed on Japanese TV shows.
From escalator etiquette to sense of humor, CNN asked Kanto and Kansai natives to explain the clash.
Personality: Outgoing vs. reserved
Kansai people are generally perceived to be friendly, outgoing and humorous.
Many of these stereotypes are manifest in Kansai's long-established comedy scene (see below) and animated dialect (see below).
On the flip side, Kanto people are often described as polite, but cold and difficult to read.
"It's true that some people are cold, but I think most of us are just shy," explains Akira Nagao, 37, from Yokohama. "Sometimes I want to talk, but it's really hard to talk to strangers because I'm shy."
Saitama native Akiharu Katsuta, 41, attributes the Kanto region's standoffish image to migration.
Home to Japan's political and economic center, many people from outside the region move to Tokyo and surrounding areas in search of opportunities, making them all strangers in a large metropolis.
"I think some people just work in Tokyo and don't have friends," says Katsuta. "Maybe they want to talk to people but they don't have anyone to talk to."
Sense of humor: Slapstick vs. subtle
For Kansai-born Japanese, laughing at each others' shortcomings helps everyone loosen up.
But the same jokes may not translate in Kanto.
"At the office, my Osaka (Kansai) colleague made fun of another colleague from Chiba (Kanto) who is bald," says Teruko Nishiguchi, 30, from Nara. "He joked, 'Where is your hair? So bald!' and that shocked the bald guy."
Is Seiji Ozawa flashing that outgoing Kansai humor? Who knows? The famed conductor studied in Tokyo but was actually born in China.
Kansai people's words sound harsh sometimes, but they aren't meant to be, says Nishiguchi.
"If I fall down the stairs, it's embarrassing," says Nishiguchi. "I want people to laugh at me so at least we can have fun. But I think Kanto people are too uptight to acknowledge their embarrassment."
In fact, many of Japan's most famous comedians hail from Kansai, including comedy duo Downtown (Hitoshi Matsumoto and Masatoshi Hamada).
The country's biggest comic powerhouse is Osaka-based entertainment conglomerate Yoshimoto Kogyo, known for "inventing" Japan's unique manzai standup comedy style.
Food: Robust vs. refined
If you've been to Japan you might have noticed a difference between udon soup in Kanto and Kansai.
The stock (dashi) is made differently.
In Kanto, it's made of dried bonito flakes (katsuobushi), creating a more pungent flavor compared with the dried kelp-based (konbu) stock that Kansai natives are used to.
Kanto soup stock is generally considered to be more robust than Kansai's. But this seems excessive.
"The soup in Kanto is kind of black. That's normal for me," says Kaneko. "But my Kansai friends were surprised when they saw the color. They said it looked salty."
The general opinion is that food in Kanto is stronger in flavor, while Kansai tastes are more subtle and light.
Similarly, natto, fermented soybeans known for its slimy texture and powerful smell, is a common breakfast food in Kanto, while Kansai people are less likely to enjoy it.
Common foods such as okonomiyaki (a savory pancake) and takoyaki (octopus balls) are also eaten differently.
"For Kansai people, okonomiyaki and takoyaki are like [main] dishes. We eat it with rice," says Kyoto native Masahiro Tsuchiya, 32. "But Kanto people think of these foods as a trend from Kansai and eat them as snacks."
Escalator etiquette: Left vs. right
It's nationwide protocol to stand on one side of an escalator to allow those in a hurry to pass by on the other side.
But in Kanto, people stand on the left side, while Kansai people stand on the right.
"It's very confusing," says Shigeru Kaneko, 55, from Tokyo. "Sometimes, I bump into people when I'm in Kansai."
The most common explanation traces differences in historic roots.
Kanto was once dominated by samurai, who favored bearing left when encountering strangers, so that they might draw their swords more easily.
In contrast, Kansai was traditionally a region of merchants for whom it was important to protect their money and valuables, which they customarily carried in their right hand.
Fashion: Leader vs. follower
Kansai-transplant Tsuchiya likes living in Tokyo because he says it's easier to stay up on the latest trends.
That's because Tokyo (Kanto) is where Japanese trends are typically established.
Kansai people are always trying to catch up, he says.
"Young people in Kanto, especially girls who shop in Shibuya, Shinjuku and Harajuku, are more fashionable, but they look the same," says Kanto native Nagao. "In Kansai, people have their own sense of individual style."
"Women in their forties and fifties often wear bright colors, leopard print and furry coats in Kansai," notes Atsushi Suzuki, 34, from Saitama.
Kansai's equivalent of Tokyo's hyper-fashionable Harajuku is the Amerikamura (usually called "Amemura") area of Osaka.
It features the most forward fashion of the season.
Language: Standard vs. whatever that is
Travel in Kansai areas can be tricky for Kanto people, who often know only the Kanto (or standard) version of Japanese.
Thank you, for instance, is "arigato" in Kanto, but "ookini" in Kansai.
Regular exposure to the standard Japanese used in national media, educational materials and other platforms means Kansai people typically move more easily between their regional dialect and the more widely spoken version of the language.
If Kanto people think something is salty, they'll say "shoppai," but it's "karai," which means spicy in Japanese, in Kansai. In case you're wondering, people from both sides describe spicy food as "karai."
"I remember riding the train in Osaka and on the window was a sign that read: 'Be careful of cutting your finger,'" says Kaneko. "I thought maybe there were a lot of gangs in Kansai.
"But later I found out the real meaning: 'Be careful of getting your fingers stuck when the door shuts.' They used a word I've never seen in Kanto."
Dialect: Flat vs. emotional
"It's easy to learn the Kanto dialect, because the tone is very flat," says Akio Okuda, 34, from Kyoto. "Kansai dialect is like waves. It's difficult for Kanto people to study."
To Kanto natives, Kansai people sound noisy, emotional and proud of the way they speak, says Nagao.
One of his major gripes about Kansai people is that they won't speak standard Japanese, yet judge people who try to speak Kansai dialect.
On the other hand, Nishiguchi says she sometimes hides her Kansai dialect because she thinks some Japanese look down on Kansai folk.
"I hear people in the cafe, usually older women, say they don't like Kansai dialect," she explains. "I guess it sounds funny but vulgar at the same time."
Sports: Giants vs. Tigers
Rival Tigers and Giants stunned fans when they teamed up in an exhibition game against MLB all-stars in November 2014.
Whether in baseball, kendo or horse racing, teams and athletes from each region are highly competitive with each other, and so are their fans.
It's bad enough if their team or athlete loses in a local match, but many can't tolerate losing to their regional rival.
Watch a baseball game between Tokyo's Yomiuri Giants and Osaka's Hanshin Tigers and you'll get the picture.
"Tigers fans are very enthusiastic," says Katsuta. "They all hate the Giants and seeing the Giants lose is their greatest victory.
"I'm a Giants fan and I don't usually care, but the Tigers have been so strong this past year, I want them to lose now."