The front of the menu says: “Tsunami is about sharing and when you share you are giving.” Yadda yadda yadda. The mood at the moment is not about sharing. It is about getting your paws around what you can and hugging it closely to yourself. And in a Japanese restaurant there never seems to be that much of anything anyway. Furthermore, there is the resonance of this restaurant’s name. Monster waves smashing everything in their path seem not a precise evocation of generosity.

To be fair, the original Tsunami restaurant in Clapham opened several years before the disaster of 2004 and in the ensuing time memories have faded — as sadly they invariably do for people not immediately affected — while the restaurant, launched with ex-Nobu chef Singi Nakamura, has established itself and thrived. I have fond memories of eating in Voltaire Road SW4 and was delighted to find this new branch in W1, within walking distance of where I live and challengingly close to the wonderful Roka.

The narrow, tunnel-vision site housed only briefly the Brazilian bar and restaurant Boteco Carioca that went before. Its awkwardness is now emphasised by an abundance of waiting staff who are forced to congregate in the front section next to the dumb waiter, which occasionally they emulate. I watched as potential customers arrived and to everyone the first sound out of the greeter’s mouth was “Haveyougotareservation?” The restaurant was not by any means full. It is so inhospitable, so lacking in understanding of what restaurants should be there for.

It is a good idea to visit Tsunami in a party of at least four, partly because there is the opportunity to try more dishes but also because tables for two are cramped. On the first visit, taken there by friends, we created a kind of pool of intimacy and the only apparently Japanese member of the waiting staff attached himself to us in a helpful sort of way. On another occasion, two of us were left twiddling our thumbs acting as a reluctant audience to a trio of bellowing, ugly Americans who I felt sure were going to finish up, rush home and vote for Mr McCain.

The décor, with its waxy plaster walls featuring sprays of gold flowers and banquettes upholstered in pale grey leather, is faintly reminiscent of Yauatcha. The subtlety in the quite loud music escapes me but it brought to mind the dismal experience of dining at Buddha Bar. Fortunately the Nobulicious dishes are mostly very well prepared and presented and it is possible to eat quite inexpensively relative to the sophisticated Japanese norm.

Flashing, as they put it, edamame beans in butter with a pinch of spices adds to their perfection as a menu-studying snack but adding £2 for that process to the basic edamame at £3.50 seems unwarranted. The word “sunkissed” is used to convey searing salmon and tuna in hot olive oil for the nanosecond it takes to remove fear of the completely raw. The salmon slices are served with ginger, chives and sesame oil and the tuna slices with yuzu ponzu sauce. Both are excellent. We also liked very much the delicate steamed snow crab shu mai (dumplings) and agedashi tofu, the cubes fried in tempura batter.

In true Peruvian/Japanese style jalapeno chilli enlivens the yellowtail sashimi, also dressed with coriander and garlic, and, looking at the menu in front of me, I see I missed yellowtail tartar, which is mixed with wasabi-coloured flying fish roe (tobiko), truffle mayo and a wasabi ponzu dressing. That will be for next time. From the long list of appetisers don’t omit nasu goma, chunks cut from long, slender aubergines imbued with miso and grilled. On both occasions we requested that delicate savoury custard chawan mushi but, although it appears on the menu with the interesting content of prawns, chicken and blue cheese, neither time was it available.

Mixed tempura, a collection of shrimps and vegetables, was correctly prepared and good value at £7.50 to share between four. We also liked the timorous purity of steamed tofu with choy sum, broccoli, lotus root and shitake mushrooms dressed with sake and soy sauce. Grilled black cod marinated in sweet miso (gin dara) may have become a cliché but for good reason. It is so shamelessly easy to like. Just as appealing was chargrilled lamb, where slices of delectable meat were layered with oriental mushrooms and a peppery sauce.

There is a menu of sashimi, nigiri sushi and sushi rolls, some, like the special roll incorporating tuna, snow crab, salmon, white fish, sweet shrimp, avocado, kampyo (dried gourd) and tamago (sweet omelette) at £9.90, pushing the boundaries of the definitions. Desserts include a steamed pudding made with Calpico served cold with red beans and mango, and exotic fruits and fondant for the unadventurous. In the spirit of the enterprise there are also dessert cocktails. Cheeky Nipple made with Baileys, Kahlua, Grand Marnier, whipped cream and a chocolate button is one. In the spirit of not so much sharing as conserving we stayed with Japanese tea.

Crunchy tip: there is currently 20 per cent off the food bill at lunchtime and before 7pm at dinner.