This page offers a guide on grabbing the Shine Sprite in Episode 4 of Sirena Beach. This area is accessed via the pipe on the roof of the house at the Plaza Square once you’ve cleared Episode 6 of Pinna Park and defeated Shadow Mario back in Delfino Plaza.
For the first time since Episode 1, this Episode will take place outside of Hotel Delfino. Make your way over to the Hotel Manager once again to discover that Manta has been spewing its electric goop everywhere and he’ll task Mario with cleaning it up. There is one catch however, you’ll have three minutes to clean the entire area so get to it!.
This is all down to your skill with FLUDD and it may take several times until you get it all. Be sure to be on the lookout for water barrels, Ground Pound these to scatter water over a large surface, making your life a lot easier. Once the entire area is clear, return to the Hotel Manager to report your success and claim your Shine.