Sushi is seen as by the world as the definition of Japanese food. Now you're in Japan, it's time to eat the best Sushi you will ever devour.
Sushi is a food that is readily available across Japan. You can get it at every connivence store, Train Station, Supermarket, even sometimes at McDonalds, and usually your not too far from a Sushi Restaurant.
Whilst in Tokyo be sure that you try your luck at some of the best regarded Sushi Restaurants in town.
If you make it down to the Tsukiji Fish markets in the early morning, be sure to take the ritual of having fresh sushi for breakfast from the many stands serving. If your up for the best of the best, and don't mind waiting, if you have the patience try Sushi Dai. This is considered the best Sushi restaurant at the market, but bring a book, the wait is usually 2 hours +. However those who do it, say the wait is worth it.
Tsukiji Market.
Another great spot, may not even be noticeable it's that small. It's located in old Tokyo in Asakusa just opposite the US Embassy in Japan. Sushi Saito it has been awarded 3 michelin stars and it's lunch isn't cheap at over 5000Y per person, but flavour, and freshness is certainly worth it.
For good value, and amazing Sushi, be sure to try Fukuzushi in Roppongi Hills. The restaurant has been open since 1917, and in the back streets of Roppongi for the last 40 years. Try and get seats by the counter, and watch the master chefs created a amazing meal right in front of your eyes.
Whatever you are feeling for, make sure Sushi is part of your Japanese experience, and it will be difficult going back to Sushi in your home town.