To find Sakura Bloom, you must destroy the pink and purple Electro clusters that form in the Inazuma region with an Electro attack. Any other attack and nothing will happen to the cluster.
Local Specialties respawn every two days after looting them; however, this is based on the time you harvested them, not the server reset time.
The image below shows where you can find Sakura Bloom in Inazuma.
Click on the image to enlarge.
- Type: Local Material
Sakura Bloom is used for the following Character Ascensions.