Mt. Kobo is a great place to have a picnic (hanami) while the cherry blossoms bloom. There are about nine kinds of cherry trees and 4,000 individual trees on the hill. The entire hill turns pink when the trees are in full bloom, which is an impressive sight.
You may want to go at night and see the many Japanese lanterns lit up, hanging between the trees. You can take drinks and snacks and sit under the blossoms. Then take a walk to the top and look at the stars and a view of Matsumoto by night.