I like Yo Sushi a lot but I think Moshi Moshi is a tad better.
Moshi Moshi are only in London and Brighton. Its the same concept, conveyor belt and colored dishes but they reckon they were there first, so there you go.
We always feast on 'proper' sushi when we go back to NY. There is a restaurant near my folks that does half price rolls during the day. 
Moshi Moshi is amazing! If you go on their website and sign up you get a membership card you can save ALOT of money, on sunday they do £1.70 day where everything on their belt is £1.70 and on your birthday they send you a voucher for a free meal, so i always go with a friend and we spend £100, get half off and it only costs us £25 each!
And it's SOOO easy to spend £100 if you have the conveyor to start then have the teriaki steak, which is probably the nicest steak in the world, just amazingly delicious!
Plus wine and copius amounts of sake
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I do Yo rainbow with my friend the other day, we also order it for delivery sometimes, it always comes piping hot and is really nice but it isn't as authentic as moshi moshi, it's a lot of crab sticks and california rolls. I really like the sashimi they do though, especially that coriander seared tuna, it's lovely.