Hirosaki in Aomori Prefecture is known for its Cherry Blossom Festival held in the park surrounding Hirosaki Castle. A fairly huge park, I must say. The blossom peak is during the Japanese "Golden Week" vacation period (late April-early May). So expect lots and lots of people. If you come early in the morning, say by 5 am, (this is what I did) then you can find a nice quiet spot. Also, early in the morning, the light and color are at their best!