Tokyo treasure: The food at Japan's most exclusive restaurant Mibu can literally make you convulse with pleasure

As we began our descent into Tokyo Narita airport, the happy memory of my in- flight meal of grilled eel, steamed sea-urchin roe and simmered monkfish liver, courtesy of ANA, was only just fading. But, as I looked out on to the carpet of lights below, as usual when arriving in the Japanese capital, I was already planning my next meal. And the one after that.

Other than stuffing my face, I was here to attend the first Asian culinary "summit", Tokyo Taste, held in Tokyo International Forum. The event turned out to be the greatest ever gathering of haute cuisine and "molecular" chefs the world has seen. At one point gathered on stage were Heston Blumenthal, Ferran Adrià, Joël Robuchon, Pierre Gagnaire, Nobu Matsuhisa, Juan Mari Arzak, Grant Achatz, and a dozen other starred chefs from Japan, China and Italy.

They were here to acknowledge a debt to Japanese cuisine that dates back decades. Since the Tokyo Olympics of 1964, chefs from Europe and America have made pilgrimages to Japan to pilfer ingredients, techniques and presentation styles. Nouvelle cuisine was born of that first visit by the chefs of the French Olympic team, while the elaborate, multi-course kaiseki meal remains a key influence on many leading chefs. Over three days, the chefs demonstrated some of their Japanese-influenced signature dishes – Blumenthal gave us his umami-packed "Sound of the Sea"; Adrià offered tricks with alginate, used for centuries by the Japanese to make tofu.

At the end of his demonstration, Adrià invited a short, elderly Japanese man to the stage. They embraced like old friends, and Adrià introduced a film of a visit the Japanese chef had made to his restaurant El Bulli a couple of years earlier. The two watched, each with one arm around the other's shoulder.

I recognised the other man at once. This was Hiroshi Ishida, 67-year-old chef and owner of the restaurant Mibu, perhaps the most fabled and exclusive ichigen-san okotowari ("invitation only") restaurant in Japan. Mibu is not listed in any phone book; even Japanese people cannot make reservations. You can only go if you are invited by a "member", and members are themselves only allowed to dine once a month, together with seven guests (the restaurant seats just eight).

Much to the envy of the other chefs I spoke to, Blumenthal, Adrià and their hangers-on were to eat there that night (along with half the TV crews in Japan, it turned out). I was envious for a different reason: I knew how good the food was at Mibu.

Yukio Hattori is the godfather of Japanese food. As well as being the director of Tokyo Taste, he is the leading authority on Japanese cuisine and the head of Tokyo's largest cooking school, Ecole de Cuisine et Nutrition Hattori. In Japan, he is most famous as the on-screen commentator for the flamboyant TV cook-off show Iron Chef, which launched the careers of Nobu, among others, and became a massive hit in the US.

I had first met Hattori at his school in central Tokyo while travelling through Japan researching my new book on Japanese food, Sushi and Beyond – What the Japanese Know About Food. Hattori, immaculate in his trademark frictionless, black, silk Mao-style suit, with heavily-oiled silver hair and a deep tan, talked about how he had been the first to open the eyes of Western chefs such as Robuchon and Adrià to Japanese ingredients such as yuzu, dashi, wasabi and miso paste. "We have had molecular cuisine for 40 years or more," Hattori told me. "You know the fake caviar they make with tomato juice, or whatever? That was in Japanese markets 40 years ago. When I introduced Ferran to yuzu six years ago he went crazy for it, same with miso, fresh wasabi and katsuobushi."

As the interview drew to a close, I asked Hattori to name the best restaurant in Japan. "Ah, the best restaurant? It is not open to the public, only members, and you won't find it in the Yellow Pages or any guide book," he said with a beatific smile. "I took Ferran there. He cried when he ate the food. The chef is a true master." "Wow," I said. "It is now my greatest ambition to eat at that restaurant." Hattori looked me in the eye, and then looked down at his hands for a moment, as if mulling something. He looked back up. "You will come with me," he said. "What, you mean to see the restaurant?" ' Hattori took out a small pocket book. "No. To eat: 30 October, 6.30 in the evening. Meet me outside the Sony building."

That evening, Hattori led me and his other guests – all Japanese – through a maze of dingy side-streets to an anonymous, strip-lit staircase. It looked more like the entrance to a multi-storey car park than the world's greatest culinary secret. At the top of the stairs we were greeted by an imposing woman in her early sixties, dressed in a magnificent dark kimono. Mibu has but one small, low-lit, windowless dining-room, given over to the member and his guests each evening. Its traditional pale clay walls were timbered with hinoki wood, as used for the coffins of emperors. But Mibu was neither glitzy nor ostentatious. The tatami room was decorated with just a scroll and a vase – albeit both, it turned out, priceless.

Chef Hiroshi Ishida has run Mibu for more than 30 years, his wife explained as she offered us tea from a pot with an unusually long spout. She poured it from a height, as you might ouzo. "When there was a risk of poisoning, if you poured like this the oxygen would mean the tea was less acid and there was less danger," she said, adding that the pot was worth 1m yen (about £6,500). She drew our attention to the scroll on the wall. It was of a dancer. "This is 70 years old. See how she is drawn with one unbroken line. We get power from art," she said quietly, almost to herself, as she left the room.

"The chef has a real appreciation of the four seasons," Hattori said. "I have been coming here 12 times a year for 16 years, and every time is an evocation of the month we are in."

Ishida's wife brought some grilled ayu, a seasonal river fish. "It goes well with sake. Note the bitterness of the guts," said Hattori. The fish, famously caught by fishermen using trained cormorants, had been grilled whole, including the innards, and was served in a plain paper cone. Mrs Ishida showed me how to pinch the flesh on the tail together to release it from the bones, and then eat around the spine.

Mrs Ishida returned with a plate of bonito sashimi, a glistening rainbow of purple and red. Was it the greatest sashimi I'd had? No question, not least as it had some texture and bite, unlike so much mushy, freezer-burnt raw fish in the West.

Aubergine was next. Often, Mrs Ishida said, chefs reject fruits and vegetables late in their season, but her husband relished working with vegetables other chefs might think were past their best. The aubergine was slippery and fall-apart tender, with a super-intensified taste.

Until now, the meal had been revelatory and delicious, but things took a turn for the transcendent with the next course, hamu, or pike conger eel, served in a dashi with yellow chrysanthemum petals scattered on its surface. I took a sip of the gently steaming broth and literally convulsed with pleasure. Hattori saw my reaction, smiled and nodded to himself. "You see, I really wanted you to try a proper dashi," he said. "This is the number-one dashi in Japan. Usually restaurants prepare dashi in the morning, but here it is prepared right at this very moment, the katsuobushi is shaved at the last minute. The smell of dashi evaporates quickly, so usually there is only a faint trace, but here you get the full flavour."

My shudder was involuntary, like a mini orgasm. The soup had a deep meatiness, an addictive savoury foundation, and above that danced teasingly tangy notes of the sea.

"You know," said Hattori. "Ishida just came up with this dish this afternoon. In 10 years, I have never eaten the same dish twice. That is almost 200 dishes, all different."

"But, but..." I stammered. "I don't believe it. It is like this dish has always been around. This dish must have existed before, it is so good." "That is just what Ferran Adrià said when he ate here," said Hattori, triumphantly. "He said it was as if Ishida-san's food must always have been with us."

"Customers are like patrons of artists for us," Ishida's wife told me. "This food is not something you can buy with money. God gives you the time to enjoy this moment but you need to have the ability to enjoy the moment, which is priceless."

Ishida-san himself brought dessert – a kogyoku apple from Gunma prefecture, cooked in thin slices and as light as a communion host. I stood up to shake his hand, but he gestured, smiling, that I should sit. I asked where he got his inspiration from. "It is very difficult. But I am always looking to get better at what I do every month," he said. "He is competing against himself," said Hattori. "Nobody can cook like him."

In the West it's almost a cliché for chefs to claim that their food is "seasonal, fresh, local and simple", before presenting us with plates of foam, sous-vide this, jellified that and puréed the other. I spent a year training to make this kind of food, then working in Michelin-starred Parisian kitchens serving it to customers, with precision-placed chervil leaves, sticky reduced stocks and absurdly turned vegetables. But at Mibu, the plating was elegant but the food looked as if it had simply "arrived" in position. Above all, Ishida had a humility – to the ingredients, to his peers, to his work and his guests – that would be utterly alien to most Western chefs.

There was a poignancy to our meal at Mibu, too, an elegiac quality which, had it not been such a joyous sensual feast, might almost have been melancholy. The dishes he had created especially for us that evening – never to be repeated – were born of a lifetime's experience and a depth of understanding of Japanese culture that few Japanese chefs could match, and even fewer will attain in the future.

By the doorway, I asked Ishida's wife how old her husband was. "Sixty-five," she said. "Oh, he can go on cooking for years yet," I said. "No,' she said quietly, so that he couldn't hear. "By cooking, he is cutting his life short."

'Sushi and Beyond' by Michael Booth is out now (£12.99, Cape). Michael flew to Japan with ANA (0870 837 8811, www.anaskyweb.com), which operates a daily non-stop service from Heathrow to Tokyo from £598 return. He stayed at the Peninsula Hotel (0800 2828 3888, www.peninsula.com). For information on visiting Japan, go to www.seejapan.co.uk