This page offers a guide on grabbing the Shine Sprite in Episode 1 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 4 of Pinna Park and defeated Shadow Mario back in Delfino Plaza.
Taking on Manta
As soon as you enter Sirena Beach for the first time, you’ll notice what seems to be a peaceful hotel resort. Head up the stairs and you’ll find the hotel manager standing by the infected pool. Speak to him and the large Manta will return, spreading electrified goop in the process so have your trusty FLUDD at the ready.
You can remove this by spraying it but doing so will soon see the shadow of Manta soon approach you. Spray Manta with the Fludd while removing the electrical goop around you and Manta will begin to divide, creating smaller ones. Continue to focus on any that gets too close and eventually they’ll become more aggressive and start charging towards you. Use circular sweeping motions and use the Hover spray if too many get too close, defeat them all and the hotel will return along with a Shine.