March- April is the time to be in Japan to view the blooming of cherry blossom. You can get the exact date of the bloom at a particular place online. We were in Japan in March- April '17 and experienced Sakura( cherry blossom) viewing ( the event known as Hanami). We experienced Hanami in Tokyo(Yoyogi park,Gyeon National Garden, Ueno Park, Yanaka cemetery ,Nezu shrine, Chidorigafuchi , Inokashira park,Toyoma park ,Imperial palace east gardens and Sumida park) and Hiroshima (Hiroshima castle and Miyajima).The cherry blossm lasts only for 1-2 weeks.The Japanese families gather below the trees and picnic eating and drinking.I would recommend Yanaka cemetery,Chidorigafuchi(go during evening and see the lights),Gyeon national gardens,Inokashira park and Sumdia park in Tokyo for hanami.