How does Sara become a child in Mermaid Melody? - Anime & Manga

I watched this anime when I was in grade 4. I still can't see why Sara (the orange mermaid) becomes a child.

Mermaid Melody: Pichi Pichi Pitch (TV) - Anime News Network

Mermaid Melody Pichi Pichi Pitch

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How does Sara become a child in Mermaid Melody? - Anime & Manga Stack Exchange

Mermaidmelody Stories - Wattpad

Mermaid Melody Magical: Hanon Hosho (my favourite mermaid!!!)

Mermaid Melody - Assoluto Amore: with Sara

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Incorrect Mermaid Melody quotes, and more! — Sara, pacing nervously: Uhh Gaito, sighing

How does Sara become a child in Mermaid Melody? - Anime & Manga Stack Exchange

CDJapan : Mermaid Melody Pichi Pichi Pitch Rina Toin A3 Matted Poster Collectible