Mermaid Melody Pichi Pichi Pitch Pure

Synopsis

To cheer up a crying Lucia, Hanon and Rina take her to a karaoke joint, which just happens to have their songs. They sing and get horrible scores on their own songs! Being angered by that, the three transform into their idol forms and sing, causing Lanhua (who was the cause of everything) to go capture them. Rihito gives Lucia a ride to nice scenery and offers her a gift; however, he is surprised to hear that the only thing she wants is Kaito.

(Source: Wikipedia)