We had a Japanese restaurant close to us that had the most amazing sushi.
The decor was awful, like my grandmother's living room and the restaurant itself was above a shop with limited signage. If you didn't know it was there you'd never have found it.
The owner was an ancient Japanese man who made the sushi to order at the counter and it was the best sushi we'd ever had.
Unfortunately a few years ago he told us that the landlord was increasing the rent so they were closing the restaurant.
We live in an area of London with a high percentage of Japanese residents so there's a lot of choice of Japanese restaurants but we've never found one quite as good.