In Japan, you can tell where you are by the colour of your miso soup. If it's sweet and white, you're somewhere in the country's western half; if it's dark and salty, you're in the east.
The miso divide is a serious matter. If a man from the west marries a woman from the east, the first thing they have to decide is which type of miso the household is going to eat.
We take the miso test on our first morning in Tokyo.
We have decided to do as the locals do, and grab a cheap and cheerful breakfast at a fast food eatery, a gyudon ya, named after the big bowls of beef and rice that are a popular option.
We line up at the ticket machine to order a typical breakfast set. It's served on a neat little tray, divided into portions which each need to be unwrapped separately. It feels a bit like Christmas.
The first thing we check out is the miso soup. Yep, dark and salty. We're definitely in Tokyo, Toto.
Our tray also includes a serving of steamed rice and fresh green sheets of nori: wrap the seaweed around a section of rice; eat; repeat. There's even a fried egg, a touch of home which brings smiles to some faces - until they realise they're going to have to eat it with chopsticks.
Then there's the natto.
Natto is the Vegemite of Japan and, like Vegemite, it's an acquired taste. The fermented soybeans are not particularly attractive - they're a bit of a stringy mess - and the aroma could politely be described as rich.
I fold a morsel into my mouth.
It has a dark, malty taste that reminds me of Ovaltine. I'd still prefer a croissant with raspberry jam, but if it's a choice between Vegemite and natto, I'll take the natto.
There's no better way to get beneath the skin of a culture than through its food, and each meal we eat in Tokyo brings a new revelation. And we get through a lot of meals.
In just a couple of days, we order up plates of skewers at a yakatori restaurant in a narrow alley, hunker down over steaming bowls of shabu shabu, fry omelettes on hot grills and taste test our way through several different styles of sake.
In between, we sample all kinds of street food, from citrus jellies to steamed rice flour balls sticky with sweet soy sauce, to the rich French pastries beloved by the Japanese.
Our guide, Yuka, quickly proves to be an invaluable dining companion, not just because she can actually read the menu, but for the way she infallibly guides us to one delicious restaurant after another.
There are a lot to choose from.
I suspect the Tokyo city authorities, concerned lest any citizen should fall victim to hunger pains, have passed an ordinance to ensure that no Tokyoite has to walk more than three steps to the next foodstuff.
I've never seen so many restaurants crammed together in endless rows - all tiny, and all reasonably priced.
Even the arches of the railway bridges have small eateries crammed into the spaces beneath. Some have fish drying on racks outside; in front of others, dumpling steamers billow with fragrant steam.
If you don't have time to sit down for a meal, you can pop into a 7-11 and pick up a beautifully presented bento box, or grab something from one of the vending machines that litter Tokyo's streetscape.
Most of these are fairly straightforward devices, but there's a particular beverage vending machine at Asakusa station that makes helpful suggestions for which drink you should be ordering.
Every time I stand in front of it, it suggests I'm in need of some green tea. Given I don't drink green tea, it's probably right.
I am tempted to hang around and see how many people obediently follow the machine's instructions, but we have places to go and food to eat.
On this particular day, our destination is the Isetan department store.
Japan's department stores are renowned for their spectacular basement food halls, and Isetan's is perhaps the most glorious of all.
We spend an hour wandering from one counter to another, checking out foodstuffs from around the world. There are Chinese dumplings and Thai curries and custard-filled tarts, as well as more traditional treats such as gyoza, red bean cakes and sushi.
I could easily spend another hour exploring the various foodstuffs, but we have an appointment at a different sort of culinary wonderland.
Kappabashi is Tokyo's pre-eminent destination for all things kitchenware. The street is lined with shop after shop displaying elegant crockery, lethal-looking kitchen knives upon which you can have your name inscribed, beautifully crafted bowls and tea cups made of wood, lacquered bento boxes, and countless other delights.
Most intriguing of all are the shops filled with plastic food displayed by many restaurants, small works of art that look intriguingly real.
They're the most expensive things around.
Our trip is not all shopping and scoffing. We also get our hands dirty, making soba noodles with a soba master.
Hashimoto-san makes the noodles at one of the city's most acclaimed restaurants.
His soba demonstration leaves us slightly aghast at the amount of work that goes into making something as simple as noodles.
Take the kneading process. Once Hashimoto-san has rolled the dough into a smooth ball, I think we're finished - but we're only just beginning. First, he painstakingly folds the dough into a series of chrysanthemum petal shapes.
Then he smashes down hard on it, before taking a rolling pin and rolling it into a circle. Once he's achieved a lovely smooth circle, he rolls it into a square. And on it goes. This is not what you'd call fast food.
Fortunately we are working in pairs, so the workload is halved.
In the end, our noodles look presentable, even if some of them are a trifle thicker than is standard.
Hashimoto-san cooks them up for lunch, and they taste delicious. They're not a patch on the master's but they are certainly good enough to eat.
On our last morning in Tokyo, we get up early for a very special breakfast. The Tsukiji Fish Market, sadly slated for relocation in 2016, has become one of the city's biggest tourist attractions, with visitors queuing up to attend the 5.30am fish auctions.
If you want to be sure of getting a spot, you have to show up about 3am. Only one of our group is keen enough to make the sacrifice.
The rest of us front up at the more civilised hour of 6.30am.
This is peak hour at the fish markets. Tsukiji is known for its endless stalls of super-fresh seafood: glossy squid, oversized octopus and abalone.
There are the slabs of bloody tuna steak, and things we just can't put a name to - thread-like fish coiled up in layers like a lasso, shellfish with strange spikes.
The most surprising thing about Tsukiji is the smell. There isn't one. This is despite acres of raw fish, temperatures of 36 degrees, and no visible refrigeration. Whatever their system is (and I suspect it involves copious amounts of water sluicing through), it works.
Numerous restaurants are already open, serving up sushi and sashimi straight off the boat.
I'm usually not interested in any food this early in the morning, particularly not raw fish, but since we're here, I try a few pieces of sushi. This is perhaps the freshest seafood I've ever tasted: definitely worth getting up for.
The writer travelled courtesy of Intrepid Travel.
GETTING THERE Jetstar flies to Tokyo Narita Airport. See jetstar.com.
TOURING THERE Intrepid Travel's Japan Real Food Adventure is a 12-day trip that takes in Tokyo, Nikko, Koya-san, Kyoto and Osaka.
Highlights include a visit to a sake brewery, sampling Buddhist cuisine prepared by monks, and a visit to a fugu restaurant to sample the infamous poison fish. Rates start from $4795 each , and there is at least one departure a month between next month and November.
MORE INFORMATION jnto.org
FIVE MORE TOKYO TREATS TO TRY
CURRY RICE Japan's favourite comfort food is surprisingly sweet, thanks to the addition of apples and honey.
MONJAYAKI A Tokyo specialty, these runny omelettes are most delicious when made with cheese.
YAKI ONIGIRI Triangular rice balls stuffed with anything from cod roe to sliced beef are available at every convenience store.
TAIYAKI Warm up on cold days with this fish-shaped pastry stuffed with azuki bean paste, chocolate or cream.
KARAAGE You'll find this tasty fried chicken, spiced up with soy and ginger, in every izakaya.
- FFX Aus