To the average Japanese (and Tokyoite), Sakura season is huge. It is the most important time of the year for family outings, romantic rendezvous', and A LOT of pictures.
Sakura viewing (or Hanami)
Most of the crowds gather at the bridges dotted along the river for the perfect photo opportunity
Rosé and Sakura? Word...
Restaurants and business establishments in the Meguro-ku area of Tokyo donate to the festival every year, and in return get a Lantern to decorate and hang.