The Tokyo Restaurant That Has Cooked One Fish Since 1830

Isegen opened in 1830, in the last decades of the Tokugawa shogunate. It is still in the same trade, in the same neighbourhood of Tokyo, in a wooden building with a tiled roof that looks nothing like the offices around it. For 196 years it has served essentially one fish.

That fish is anglerfish — ankou. Hiroyuki Tarumi, 43, is the seventh generation to run the place. He arrives by motorbike at 7:15, fills a stockpot with water, and starts the day the same way his predecessors did.

On the morning filmed here, three anglerfish had come in from Hokkaido. The biggest was close to 8 kg. None of them were laid on a cutting board. Anglerfish is broken down hanging.

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What ankou nabe actually is

Anglerfish is an ugly, gelatinous, bottom-dwelling fish with almost no bones you would call bones, and in Japan it is a winter delicacy rather than a curiosity. Ankou nabe is the hotpot built around it: skin, flesh, cheeks, fins, stomach and liver simmered at the table with vegetables and tofu.

The liver, ankimo, is the prize. It is rich, dense, and closer to foie gras than to anything else you might compare it to. It is also the reason a single fish can be worth several hundred dollars.

Most versions of the hotpot are made with miso. Isegen is not, and the reason turns out to be geographic. More on that below.

The name comes from an apprenticeship

The first owner was a man called Shozo Tachikawa, who had served an apprenticeship at a shop called Iseya. Shozo of Iseya became Iseshou. When the second generation, Genshiro, moved the business to Kanda, the name changed again — Isegen. It has not changed since.

A photograph from about seventy years ago hangs by the entrance. It shows the current owner’s father as a small boy. Tarumi keeps it there, he says, because he likes the idea of being watched over.

Asked whether he had ever considered not taking the shop, his answer is short. He always meant to inherit it, circumstances made it happen earlier than planned, and he grew up on the proceeds of this room. He also happens to like the hotpot.

He joined in 2007. Nearly twenty years behind this counter.

The morning starts with dashi

Water goes into the pot with Rishiri kombu and soda-bonito flakes. Then roughly an hour of careful heat, bringing it to just short of a boil. Take it over the line and the balance of what you extract changes; bitterness comes with it.

Just before boiling, the kombu comes out and the katsuobushi goes in. Another hour or so, skimming as it goes. At the end the whole thing is tipped into a cloth bag, flakes and all, and wrung out. Nothing is left behind.

Broken down hanging

At 8:08 the staff arrive, and so does the delivery from Hokkaido. Tarumi puts on an apron and takes out a knife.

Anglerfish is mostly water and the flesh is slack, so it will not hold its shape on a board. Instead the mouth is hooked onto an overhead frame and the fish is cut standing up — the tsurushi-giri, the hanging cut.

Fins off. A cut through the skin, then the skin is peeled away. The guts have already been removed at the port, so that step is skipped. The collar comes off each side, then the long central fillet. A whole fish takes a few minutes.

A small one yields about ten portions of hotpot. Only about a third of the animal is edible at all.

The slime is the freshness test

When the second fish goes up, mucus hangs off it in icicles. Anglerfish has no scales; the slime is what protects the skin. It is also a defence — a predator that gets a mouthful of it tends to give up and leave.

And the slime keeps coming out after death, which makes it a clock. A fish that has stopped producing it, and has gone glossy instead, is past its best.

If there is no slime and it looks shiny, that is not good freshness. A certain amount of slime is proof it is fresh.

They grow about a kilo a year. Five years to reach five kilos, and after that it accelerates. The 8 kg fish on the hook was probably six or seven years old. The largest Tarumi has ever cut was close to 30 kg.

The expensive part is the liver

Ankimo is where the money is. Hokkaido liver starts around 20,000 yen a kilo and has touched close to 40,000 in a strong market. Overseas demand keeps pushing it up.

The fish arrive already opened and cleaned at source, which is not a job you hand to just anyone: the supplier has to be able to judge liver quality. Tarumi describes the relationship as built on trust rather than price.

The liver pulled out of this fish weighed a little over a kilo — and even that yields barely ten portions if it is served raw as sashimi. The outer surface, which oxidises quickly, is trimmed off and diverted into the hotpot; the odd ends are pushed through a sieve and used elsewhere. Nothing is discarded.

Quality is read from colour and sheen. Heated, good liver turns an orange-pink, the same astaxanthin that colours salmon. Individual fish differ depending on what they have been eating, and cooking makes the difference obvious.

Soy, not miso — because of the neighbourhood

Anglerfish holds so much water that you can simmer the cut flesh without adding any liquid at all. That water carries flavour, but it also carries the smell that comes with the slime. The standard solution is miso to cover it and liver stirred in for richness. That is why the famous version of this hotpot is a miso one.

Isegen serves it with a soy-based broth instead. The previous generation rebuilt the recipe to suit soy when the shop was serving this part of Kanda, and it landed. It has been the soy version ever since.

The greengrocer who has been delivering here for 25 years has his own explanation for the shop’s longevity: it tastes good, and it is unusual. He adds that he is not much of a fish eater himself, but the soy broth is not fishy, so he keeps coming. On the seventh generation he is blunt — sharp operator, sources his own mitsuba and shiitake, impossible to argue with.

Prep is a fight with slime

Once the fish is apart, every part is processed separately. Pieces go into the pot in order of how long they need, come out, get cooled in water, and then the surface slime is scraped away. Only then does the flesh look like the white fish you expect.

The central fillet goes to the fryer. The cheeks go into steamed custards and clear broths. For the bone-in fried pieces, the thin membrane has to be stripped off completely — leave it on and the batter will not crisp.

Fins, ovaries and the thick, springy stomach are all cut down and go into the hotpot. Skin to organs, almost the whole animal is eaten.

The liver sits in salt water for twenty minutes — long enough to draw off the smell without stripping the flavour — and then goes into a steamer for an hour or so. A big winter liver takes an hour and a half.

Tarumi has used the same two knives for about fifteen years. When the cameraman is handed one and invited to try, the gap is visible: the professional cuts with the whole length of the blade, the amateur pushes with the tip.

Asked what took longest to learn, he says speed, and that the only way to get it is repetition. Then he adds the one thing twenty years never fixed — his hands go numb in the cold, so he wears gloves.

His own favourite is tomo-ae

Asked how he most likes to eat anglerfish, he does not pick the hotpot. He picks tomo-ae: flesh, skin, fins and stomach dressed with blended miso and liver, all on one plate.

Part of the appeal is that the whole fish is condensed into a single dish. The other part is that the seasoning varies by region and by household — there are family versions of it, the way there are family versions of anything cooked at home. He likes that it carries that.

The morning is not only anglerfish. Rockfish is blanched and washed. A bonito is salted, seared over gas, then finished with burning straw for the smoke. A large wild flounder — snow-white on the underside — is filleted. A specialist shop, but not a one-ingredient kitchen.

11:30, doors open

At 11:24 he waters the plants outside and hangs the noren, the split curtain with an anglerfish printed on it. A fish goes into the display case at the front, ice packed into its mouth and around its body, an ice bag hung above it. The glass is wiped down.

A rickshaw is already waiting outside. Isegen runs it as a pick-up service — a tour of the neighbourhood, a run to Kanda Myojin shrine. You can book it, and you can also just flag it down on the day, whether or not you are eating.

Lights on, floor swept, sign flipped. At 11:30 the doors open and customers come straight in.

The menu

The hotpot holds skin, flesh, stomach, cheek and liver, with udo, shiitake, ginkgo nuts, snow peas, shirataki, grilled tofu and cut mitsuba. The broth is poured in, the pot goes on a burner at the table, and it is lit with a match.

There are instructions. Simmer it properly — long enough that the broth colours the white flesh and the udo — because that is when the flavour goes in. The mitsuba wilts first. Leave the liver until later: it deepens the broth, and the rice porridge you make at the end will be better for it.

In summer there is also a chilled tantanmen with ankimo paste in the soup and more paste on the side to stir in. A deliberate move to keep anglerfish out of the winter-only box.

The sea, and the fields

Asked at the end of the day what he is putting effort into now, Tarumi talks about ingredients rather than dishes. He sees it as part of the job to carry what the producers intend through to the plate, so he goes to the ports where the anglerfish lands and to the farms where the vegetables grow.

Two of those vegetables — cut mitsuba and udo — are native Japanese crops with a shrinking number of growers, and he cannot serve the hotpot without them. He would like to get involved in the farming side, gradually.

The same thinking applies to the fish. He wants the catch to still be there in the future, which means stock management, which means being the kind of restaurant whose opinion carries weight.

Anglerfish reads as a luxury. He points out that the hotpot plus the rice porridge at the end comes to around ¥5,000 — priced, deliberately, for a small indulgence or a family occasion rather than an event.

I would like people to be able to come to this food culture casually.

If you are going

Hours and closing days shift with the season. Worth confirming before you go.

The part text cannot carry

Everything above is the reporting. What it leaves out is the handling — the angle of the blade going under the skin, the way the mucus hangs, the moment heat turns the liver orange.

The hanging cut starts at 5:03. The hotpot is finished at 31:32.