This out-of-season fireworks display takes place every Saturday in December (10th, 17th, 24th, 31st) at 7pm. The fireworks are shot into the sky between Odaiba and the Rainbow Bridge—so there are some awesome photo opportunities.
Best viewing position is in front of the Decks shopping center. Expect it to get more crowded as the end of the year approaches.
Check out this post on a night out in Odaiba here.