I tried Tetsu last Saturday night (their 6th night of their soft opening week). They don't have a website yet and they didn't even have a phone number until very recently (it wasn't printed or to be found anywhere and I had to ask them when I was there - it's 020 3217 0090; they're closed Saturday lunch and the whole of Sunday but otherwise open; last orders at 14:00 and 22:00 respectively).
7 seats at the counter in front of the sushi chef and 2 tables of (I think) 2. Just Takahashi-san who started in Kobe and last worked at Nobu London for 6+ years; and his charming wife (Harumi). Takahashi-san's English is very good (he graduated from a Japanese university with an English/British culture degree) and as mentioned above, he's more than willing to talk and banter.
Everything is still new so, for example, there were currently no desserts, there are only four sakes on the list at the moment and they had run out of egg by the time I arrived (near the end of the night). They do have a menu but rather than waste time with that, I just went for omakase in the true sense - being fed until I asked to stop without any idea how much until the end.
The flavours of the fish were left to speak for themselves with only things like a few drops of juice, some salt, a lick of sauce or a quick blowtorch to complement/enhance the flavours. It was sushi in a traditional but refined form (no fusion) and similar to what can be found in many good sushi places across Japan (even in airports like Haneda in Tokyo) and in countries like Hong Kong (e.g. Sushi U in Central now closed) but rarely in London.
As far as I'm concerned for best sushi in London, Tetsu's only other contender is Shiori which I love. Shiori is more refined than Tetsu (no surprise given that Takagi-san there trained in Kyoto) and Shiori's plates of food are works of art unlike Tetsu which is simply "raw" (in a nice way). None of the other places in London work for me. Dinings is fusion and doesn't have the fresh clean taste which I prefer (sometimes it works but other times not). It's the same for Yashin plus they have their frankly silly hangup about providing soya sauce. (Tetsu do provide soya sauce without having to ask.) Finally, there's Mitsukoshi which is traditional but lacks refinement.
What I found pretty unique in London about Tetsu was the omakase experience as mentioned above. Tetsu was the closest I've come so far to how I feel in Japan.
No wonder! I have a booking for Yukimura next month and I was wondering why I was quoted JPY 22,000 + 15% for dinner but now I realise that it's outside of the crab season.