Thirty seconds walk from Takadanobaba station, you won't even need an umbrella when it rains. Just cross Waseda avenue and it is there, between the Kokusai Center Pachinko and the First Kitchen on the corner.You can eat good Sushi there, among some other things, for a decent price. Their cheapest Sushi set is one thousand yen, the most expensive is three thousand. If you order by the piece, it might be a bit more expensive.
Telephone numbers : (03) 3200-7138 and (03) 3200-5896.