もののあはれ (mono no aware) is a Japanese term for the awareness of impermanence and a sadness at its passing. No where is this more apparent than in the watching of nature and especially with the short lived beauty of the Sakura or cherry blossoms.
Hanami is the time when friends, families and strangers all gather underneath the Sakura to marvel at their beauty and is as much a part of Japan as Geishas and samurai and has been occurring for centuries.
The cherry blossoms start flowering in the south of Japan in January. The Japanese then carefully track the cherry blossom front as it moves north, arriving in Tokyo towards the end of March/early April.
Photos all taken at Shinjuku Gyoen.