The Beginning

Miku Kohinata is a young girl who live with her best friend Hibiki Tachibana at Lydian Academy. She discovered that her friend is a symphogear user and that she risk her life. Miku is quite unhappy that she can't help her.

One day, her mother send a letter and a necklace to Miku for her birthday and... She discover that she's a MERMAID?! And now, she has no choice but to find the mermaid princesses.