We don't have an address for Mr Sawada, the sushi master. Just a card with the samurai symbol of a red dragonfly and the name of a street off Tokyo's Ginza. We find the tiny dragonfly engraved beside a buzzer in an unremarkable doorway. 'This is a very extraordinary moment for me,' says Chie, our translator, as we troop up some shabby stairs. 'I could never eat here. I am not rich, I am not old enough.' She's in her mid-thirties; I think she means - 'not wise enough'.
Ordinarily you would pay some $500 in advance just to make a booking here at the table of one of Japan's most talked-about traditional sushi chefs. But then, we could never have made a booking, because Sawada serves at most eight people each mealtime and is booked up years ahead. He has given us a few minutes at the end of his day to photograph him in action.
We find a small square room made entirely - floor, ceiling, walls, chairs, counter and even the fridge - of pale lemon hinoki wood. This signifies luxury; it's used for the coffins of the emperors of Japan. There is no other colour in the room except a single pink camellia in a tiny vase on the counter.
The sushi master is solemn, shaven-headed like a Buddhist priest, and a dead ringer for Brian Cox. He shows us his knives, his charcoal stove, his rice cooker and his prep surface. His sushi is served plateless, on to the hinoki-wood counter, which is planed down after each meal until it is virgin again.
Sawada heaps rice straw on the charcoal burner, lights it and then passes a slab of bonito back and forth through the smoke. This is an ancient method, taken from the Tokyo Bay fishermen. When it's sufficiently scorched he takes the fish to the counter and cuts two finger-sized slivers from it. Beside him is a basket of warm, vinegared rice, Sawada takes a breath. He shapes his fingers into a position known as ninjitsu - aping Ninja fighters - and begins the gentle, rhythmic hand-jive that makes the nigiri sushi.
His palms move from side to side under his bent head, shaping a mini-loaf of rice. He smears it with a fingertip of wasabi. Then he lays the curved strip of lean fish-flesh over it, as though fitting a delicate piece of marquetry. He places the mouthful, precisely angled, on the counter. This is nigiri sushi, the original, unchanged in 180 years.
I have to ask him what he thinks of 'new sushi' - California roll, for example. He repeats the Japanese translation - kashu-maki - as though it's new to him. 'California roll? I find it - chaotic.'
A few months later, at 6pm in the Yo! Sushi shop in Haymarket, off Piccadilly Circus, a man is slicing a roll of raw red snapper, matter-of-fact even though he is - like all sushi chefs - on stage. The waxy flesh falls away from his knife like loam behind a plough. When he's done, using every last scrap, he starts on a beefy log of raw tuna. Shape, aim, cut, push. It's hypnotic. Soon, with some slices of bright orange farmed salmon, and a nest of shredded daikon radish and mustard cress, this will be a seven-slice Assorted Sashimi, yours for an amazing £5.
The sashimi goes on to the conveyor belt. Watching the bowls in their Habitat colours ride the track is just as monotonously mesmerising as watching the chef coddling his fish hunks: in front of the conveyor you turn train-spotter, wondering whether that piece of yellowtail and salmon roe will come round again.
The mechanical ballets of sushi and sashimi-making are an art whether you're in Tokyo, at Nobu, or at Yo! Sushi. There are differences, though. Sawada trained for six years, and at Nobu the chefs do three years before they are allowed to lay hands on the fish. (What do the novice chefs do for those three years? They wash the rice. They do the dishes. They watch and they meditate.) At Yo! the training is just two months. Across town at Nobu or at Zuma in Knightsbridge seven slices of purple, orange and white sashimi, not very different from Yo!'s Special Assorted, will cost you an easy £20, before service.
[From the Guardian-Observer tandem]