I recommend Fugu restaurant. Tokyo Minato ku ,Azabu jyuban,restaurant name is Fugutake .there are two restaurant,expensive Fugu couse restaurants and casual prices restaurants,casual prices restaurant name is Izakaya Fugutake.both restaurants will provide fresh Fugu.
Hi,you can eat Fugu end of March ,but prices is different what kind of Fugu do you want to eat,i means natural FuGu or aquaculture Fugu,Natural Fugu is expensive here.Natural Fugu season will finish end of March .
If you wanted to have "wild fugu" it might be a little bit out of season. However farmed Fugu is very common and much cheaper than wild one. To recommend the place I need to know the budget. Starting around 5,000yen till 30,000 yen more or less. Depends of the quality and the place.