Osaka is one of Japan's best cities for viewing cherry blossoms. It might be best to go to Osaka Castle to get a really magical view of the cherry blossoms.
At this festival, locals get together and enjoy themselves. Multiple stands line the streets with game and food stalls. This is a festival that is motivated more by togetherness and community rather than purely religious purposes.
If you love rock music, then you need to go to one of the best rock festivals in Japan closely rivaling Fuji Rock Festival. the festival itself takes place in Osaka and lasts for 2 days. Once the festival is over, the festivities end with a finale of spectacular fireworks.
At the end of July, Osaka becomes the home of the largest firework displays in Japan. If you are lucky enough to spend the summer in Osaka then you should not miss this display.